Introduction

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.

To detect this anomaly, the NAD rule titled “Signs of a Kerberoasting attack” implements the following logic:

1. 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.
2. Extract the cname (the name of the client requesting the TGS-REQ) and sname (SPN itself) from these qualifying sessions.
3. Group the sessions by the source IP address and client account name (cname), while aggregating sessions with unique SPNs.
4. 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.
5. 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.

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)

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.

On this same page, you can test if the rule is functional prior to saving it.

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.

From there, the analyst can navigate to the associated event, which provides a detailed breakdown of the anomaly alongside links to the affected hosts.

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.

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.

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.

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.

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.

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

The detection logic for this network anomaly is structured as follows:

1. 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.
2. Split qualifying DNS sessions into individual log lines, each corresponding to an individual request or response. Retain only DNS responses containing TXT data.
3. Extract DNS names and their associated TXT data from these DNS responses. Retain only unique values.
4. Group all resulting records by the session’s source IP address, aggregating all unique DNS names and TXT data blocks.
5. 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).
6. 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).

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:

1. Adding a rule from a prebuilt template and adjusting custom variables. In this case, the rule is classified as a system rule.
2. 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.
3. 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.
• Domain Attacks: detecting classic attacks targeting domain network infrastructures using offensive tooling.
• Reconnaissance Activity: identifying suspicious activity within domain protocol sessions (Kerberos, DCE/RPC, LDAP, DNS) resembling domain reconnaissance.
• 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.

UPD 03.07.2026: added a package of rules and recommendations that help detect the described malicious activity for companies using our Kaspersky SIEM system.

Introduction

To access compromised systems, threat actors frequently abuse legitimate remote monitoring tools. At first glance, these utilities rarely raise red flags: they are signed with valid digital certificates, often allowlisted under corporate IT policies, and fully supported by OS vendors. However, they grant attackers the ability to harvest data from target devices, drop malware, and move laterally across the network.

During a recent investigation engagement, the Kaspersky Managed Detection and Response (MDR) team discovered the ScreenConnect remote access tool being leveraged to deploy and execute an AsyncRAT payload.

A deep dive into this single incident unraveled a massive campaign distributing malicious installer archives hosted on spoofed websites. These installers masquerade as popular software like OBS Studio, DNS Jumper, DS4Windows, Bandicam, and others. In total, we uncovered more than 90 domain names localized across 10 languages. The malicious archives bundle a legitimate, signed Microsoft install.exe binary alongside a rogue install.res.1033.dll library. It is loaded onto the device via DLL sideloading and deploys the ScreenConnect service, which awaits further instructions from the threat actors.

As a result, what initially appeared to be an isolated ScreenConnect incident served as the starting point for a full investigation into the threat actor’s C2 infrastructure. Every spoofed site we uncovered followed the exact same playbook: dropping a hidden ScreenConnect remote administration service under the guise of a legitimate software installer. This allowed the attackers to maintain control over compromised endpoints, with victims ranging from individual users to organizations.

We continue to break down complex, multi-stage incidents like this in our ongoing The SOC Files series. In this post, we take a deep dive into the technical execution of the ScreenConnect attack and analyze the broader infrastructure under the threat actor’s control.

Initial incident investigation

The investigation was triggered by an alert from Kaspersky MDR, which flagged the creation and execution of suspicious PowerShell and VBS scripts spawned by a ScreenConnect process.

About ScreenConnect

ScreenConnect is a legitimate remote management utility. Kaspersky solutions detect it as not-a-virus:HEUR:RemoteAdmin.MSIL.ConnectWise.gen.

ScreenConnect was running as an Access-type service — enabling direct remote connectivity — with the server explicitly passed via the command line:

Once running, ScreenConnect created and executed a PowerShell script named Fj5NmEsp9EuKrun.ps1:

Below is an excerpt from the contents of the script:

This script configures Microsoft Defender exclusions for the following objects:

• All disks in the system: C:\, D:\, and others
• All root directories on the C:\ drive, as well as the C:\Users\Public directory
• RegAsm.exe process

Additionally, the script disables User Account Control (UAC) prompts by setting the ConsentPromptBehaviorAdmin registry parameter to 0.

Following this setup, the ScreenConnect service goes on to create a VBScript file:

The installer_method3_stream.vbs script creates five files in the C:\Users\Public directory (msgbox.txt, secret_bytes.txt, 1.vb, cap.ps1, and script.vbs) and immediately triggers their execution by launching script.vbs.

This script terminates all active powershell.exe processes to cover its tracks and executes cap.ps1 in a hidden window.

cap.ps1 reads the contents of the secret_bytes.txt file, extracts sequences matching the [SXX- pattern, and converts XX from hexadecimal representation to a byte. It then uses a 0xA7 XOR key to decrypt each byte and inverts the bit order. The resulting byte array yields a fully formed PE binary, which is then reflectively loaded into the CLR.

Within the loaded assembly, the ConsoleApp1.Module1 type contains a static method named Run. The script uses reflection (Reflection.BindingFlags) to resolve a reference to this method and invoke it.

The Run method executes a process hollowing technique (T1055.012), spawning a new RegAsm.exe process with the CREATE_SUSPENDED flag. The deobfuscated and decrypted PE image from secret_bytes.txt is then copied into its address space. As a result, the RegAsm.exe process no longer executes its original code, instead serving as a container for the injected .NET module — which, in this case, is the AsyncRAT remote access Trojan.

To establish persistence, the malware schedules a task named MasterPackager.Updater:

"schtasks" /Create /TN "MasterPackager.Updater" /TR "wscript.exe "C:\Users\Public\script.vbs" " /SC MINUTE /MO 2 /F

This task triggers every two minutes, ensuring that script.vbs — and consequently the entire loader chain — executes even after a system reboot.

Once the entire infection chain successfully executes, the RegAsm.exe process establishes a connection to the C2 domain mora1987[.]work[.]gd.

How ScreenConnect entered the system

A retrospective analysis of the incident allowed us to pinpoint the source of the ScreenConnect installation: a user-downloaded archive named obs-studio-windows-x64.zip.

The archive was downloaded from hxxps://www.studioobs[.]com/, a typosquatted domain mimicking the official site for OBS Studio, a popular open-source screen recording app. This site is present in search engine results; in this specific incident, the user landed on the malicious domain directly from a search query, a vector we analyze in more detail below.

Clicking the download button for the supposedly legitimate software triggers a request to the following URL, from which the archive is fetched:

hxxps://fileget.loseyourip[.]com/obs-studio-windows-full/gVOMs5VZ9BtlcaM

The archive contains a legitimate, Microsoft-signed executable named install.exe (87603EA025623B19954E460ADD532048), renamed to masquerade as the OBS Studio installer, along with a malicious library named install.res.1033.dll. Additionally, the archive includes an Assets folder containing both a copy of the actual software being impersonated and the ScreenConnect utility.

The complete file structure of the archive is organized as follows:

When OBS-Studio-Installer.exe is executed, it loads install.res.1033.dll via DLL sideloading. This library contains the instructions required to install both ScreenConnect and OBS Studio. The deployment relies on native Windows utilities (msiexec.exe), but the attackers renamed the standard MSI packages to look like DLL files:

• Assets\x86\Data\vcredist_x64.dll: ScreenConnect installer
• Assets\x86\Data\vcredist_x86.dll: OBS Studio installer

The contents of the vcredist_x64.dll MSI package are shown below:

The Windows Installer is launched to install ScreenConnect silently in the background without requiring a system reboot:

msiexec.exe /i "C:\Temp\OBS-Studio-Windows-x64\Assets\x86\vcredist_x64.dll" /qn /norestart

Once the installation wraps up, a new service named Microsoft Update Service is created. The command line for this service explicitly defines the connection server as r[.]servermanagemen[.]xyz.

Meanwhile, the MSI package for the actual OBS Studio software runs using a standard graphical user interface.

Expanding the investigation

The attackers’ reliance on the legitimate install.exe binary provided a crucial pivot point for our broader investigation. We discovered that this specific file was being deployed in the wild under a variety of suspicious aliases, including:

• ds4windows.exe
• crosshairx_installer.exe
• obs-studio-installer.exe
• dns jumper.exe
• glary utilities pro.exe
• processhacker-2.39-setup.exe

These file names indicate that the threat actor was disguising their ScreenConnect archives as popular utilities beyond OBS Studio. Among the fakes, we identified counterfeit installers for DS4Windows, DNS Jumper, Glary Utilities, and Process Hacker. Crucially, when we search for these utilities on major search engines, these fraudulent sites frequently appear at the very top of the organic search results. This indicates that the threat actor is actively leveraging SEO techniques to boost traffic to their landing pages.

Spoofed software portals appearing in search engine results

For example, here is how the fraudulent download portal for DNS Jumper looks:

On this page, the download button directs users to the following address:

hxxps://direct-download.giize[.]com/dns-jumper/iopbsr4hymbo7nfa1q7j

Just like the OBS Studio variant, this drops an archive onto the victim’s device with an identical structure: a renamed legitimate install.exe file, a sideloaded library, and an Assets directory containing the promised software packaged alongside ScreenConnect.

Other fraudulent websites that appear in search engine results when querying the corresponding software are designed in a similar fashion.

Spoofed websites used to distribute ScreenConnect

Notably, the vast majority of the fraudulent sites we uncovered are localized into English, Russian, and Chinese. In several instances, the pages were also translated into German, French, Spanish, Arabic, and other languages. This multi-language support underscores the global footprint of the campaign, targeting a broad user base across multiple regions.

Fake domain infrastructure

To distribute ScreenConnect disguised as freeware, the threat actor spun up an extensive network of domain names mapped across three IP addresses. We have categorized these into two distinct infrastructure clusters.

Cluster 1: 162.216.241[.]242 and 198.23.185[.]81

```
162.216.241[.]242
Country: United States
Org name: Dynu Systems Incorporated
```

The connection graph below illustrates the campaign websites tied to IP address 162.216.241[.]242, which hosts the previously mentioned www[.]studioobs[.]com domain.

Looking into the registration dates for the domains on this IP, we found that the threat actor initially attempted to disguise their sites as various gaming portals:

Subsequently, starting in January 2026, they shifted strategy and began registering fake domains designed to mimic popular freeware:

In this specific branch of the ScreenConnect campaign, the malicious archives are hosted on fileget.loseyourip[.]com. Notably, the download resource is hosted on a completely separate provider:

```
198.23.185[.]81
Country: United States
Org name: NOHAVPS LLC
```

Our analysis of this second IP address revealed that it also hosts additional resources tied to the campaign, including fake gaming sites and supplementary download links:

Cluster 2: 2.59.134[.]97

```
2.59.134[.]97
Country: Germany
Org name: dataforest GmbH
```

Below is an infrastructure graph showing this IP address and its hosted domains. Notably, unlike the previous case, this address also hosts direct-download.giize[.]com, a resource used to store distributed malicious archives.

In this branch of the campaign, the threat actor skipped game-themed lures entirely, focusing exclusively on creating fraudulent freeware sites that bundled ScreenConnect with the requested application. The domains hosted on IP address 2.59.134[.]97 were registered between October 2025 and March 2026.

The chart below shows the volume of fraudulent websites created month by month:

Breakdown of ScreenConnect delivery sites by theme, August 2025 through March 2026 (download)

C2 infrastructure analysis

In total, we identified dozens of different archives distributed across this campaign. All of them share a uniform file structure, containing the malicious install.res.1033.dll library and the ScreenConnect MSI package located at Assets\x86\vcredist_x64.dll.

In some instances, the ScreenConnect installation package also bundles a CAB archive.

This archive contains a system.config XML file, which defines the connection address for the ScreenConnect C2 server:

By analyzing these ScreenConnect installations, we uncovered additional C2 addresses, which are mapped out in the following graph:

The next graph illustrates the AsyncRAT command-and-control infrastructure:

Based on the registration dates of the C2 domains, we can determine that the campaign was launched in October 2025 and paused at the end of March. However, at the time of publication, many of the landing pages remain accessible via search engine results.

Takeaways

Investigating a single case of AsyncRAT delivered via ScreenConnect allowed us to uncover a massive, multi-domain, multi-language infrastructure designed to distribute a hidden installer for this software and further advance the attack. The threat actor disguises ScreenConnect as popular utilities and distributes it through fraudulent websites that mimic official product pages. The attackers leverage search engine optimization techniques to push these sites to the top of search results in engines like Google and Bing.

This attack chain targets both everyday consumers downloading free software from the internet and corporate networks, where remote access tools are frequently allowlisted and granted elevated privileges.

The potential objective of the campaign is to steal credentials en masse and gain unauthorized access to systems for subsequent resale on dark web marketplaces.

To mitigate the risks associated with this threat, we recommend implementing the following security measures:

• Enforce strict software installation controls: application allowlisting and blocking MSI package execution from untrusted sources
• Continuously monitor for the creation of new remote administration services and scheduler tasks
• Filter outbound traffic to unknown domains and IP addresses
• Regularly train users on safe downloading practices
• Verify the authenticity of all software sources

For enterprise users, credential monitoring is a critical mitigation strategy against the risks detailed in this article, as a leaked account or compromised system access frequently serves as a vector for subsequent attacks on the organization.  Kaspersky Digital Footprint Intelligence provides continuous data monitoring across open and dark web sources, enabling security teams to respond proactively to potential threats.

Detection by Kaspersky solutions

Kaspersky Managed Detection and Response detects the malicious activity described in this post using the following indicators of attack:

1. ScreenConnect service creation with suspicious parameters
   

   logsource:                      
       product: windows         
       category: security
   detection:
       selection_access:
           EventID: 4697
           Service File Name|contains:
               - 'e=Access'
               - 'ClientService.exe'
       selection_support:
           EventID: 4697
           Service File Name|contains:
               - 'e=Support'
               - 'ClientService.exe'
       condition: selection_access or selection_support

2. Anomalous child processes being spawned by the ScreenConnect service
   

   logsource:
       product: windows
       category: process_creation
   detection:
       selection:
           ParentImage|endswith:
               - '\\ScreenConnect.ClientService.exe'
               - '\\ScreenConnect.WindowsClient.exe'
               - '\\ScreenConnect.WindowsBackstageShell.exe'
               - '\\ScreenConnect.WindowsFileManager.exe'
           Image|endswith:
               - '\\powershell.exe'
               - '\\cmd.exe'
               - '\\net.exe'
               - '\\schtasks.exe'
               - '\\sc.exe'
               - '\\msiexec.exe'
               - '\\mshta.exe'
               - '\\rundll32.exe'
       condition: selection

Additionally, Kaspersky products detect the malware covered in this post under the following verdicts:

• Trojan.Win64.DLLhijack.*
• Trojan.VBS.Agent.*
• Trojan.PowerShell.Agent.bav
• Trojan.JS.SAgent.sb

Endpoint malicious activity can be monitored using Kaspersky EDR Expert. Specifically, security teams should look for the execution of commands and scripts containing suspicious patterns, such as XOR operations used for command and data obfuscation by malware operating on the host. This activity is flagged by the suspicious_assembly_loading_into_powershell_via_reflection_amsi and xored_powershell_command_amsi rules.

Additionally, persistence mechanisms involving the creation, modification, or utilization of scheduled tasks via the schtasks.exe utility are caught by the scheduled_task_create_from_public_directory_via_schtasks rule.

Malicious code injection into the RegAsm.exe process — leveraged by attackers to masquerade execution behind a trusted system component — is detected via the code_injection_to_unusual_process rule.

To visualize the stages of the attack, security teams can utilize Kaspersky Cloud Sandbox on the Threat Intelligence portal. For instance, this tool allows defenders to map out the entire deployment and payload execution chain originating from the initial VBS dropper.

Furthermore, the Kaspersky Threat Intelligence portal supports searching and graphing the connections between malicious domains and files involved in this campaign, as demonstrated in our adversary infrastructure analysis section.

Finally, the Similarity engine within Kaspersky Threat Analysis profiles file contents to hunt down samples resembling the original threat, helping organizations identify new or previously undetected malicious objects.

To protect companies using our Kaspersky SIEM system, there are rules available in the product repository to help detect this type of malicious activity.

• Adding exclusions to Windows Defender scans via the registry is detected by rule R241_Modification of Windows Defender exclusions through the registry. Adding exclusions via PowerShell (Add-MpPreference -ExclusionPath|ExclusionProcess) is detected by rule R076_04_Windows Defender settings disabled or changed via PowerShell.
• Bypassing the UAC mechanism by modifying the ConsentPromptBehaviorAdmin registry key is detected by rule R242_UAC disabled through the Windows registry.
• Running VBS scripts from a public directory triggers rule R290_07_Running VBScript files from shared folders.
• Creating a scheduled task that runs an executable file from a public directory triggers rule R099_01_Scheduled task started from a public folder.

For the rules to function correctly, it is necessary to configure event 4657 (Security) audit for the following registry keys:

• HKLM\SOFTWARE\Microsoft\Windows Defender\Exclusions\Paths
• HKLM\SOFTWARE\Microsoft\Windows Defender\Exclusions\Procesess
• HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\ConsentPromptBehaviorAdmin

Additionally, when developing your own detection rules or conducting threat hunting for suspicious ScreenConnect behavior, we recommend monitoring the following events:

• Creation of the ScreenConnect service with suspicious parameters
  

  DeviceEventClassID = '4697' 
  AND FileName LIKE '%ClientService.exe%' 
  AND (FileName LIKE '%e=Access%' OR FileName LIKE '%e=Support%')

• Launch of atypical child processes from the ScreenConnect service
  

  DeviceEventClassID = '4688'
  AND match(SourceProcessName, '.*\\\\ScreenConnect\\.(ClientService|WindowsClient|WindowsBackstageShell|WindowsFileManager)\\.exe')
  AND match(DestinationProcessName, '.*\\\\(powershell|cmd|net|schtasks|sc|msiexec|mshta|rundll32)\\.exe')

Indicators of compromise

Loaders

B32810973132D11AFD61CCEE222BBB79
5B7E1FE55BD7B5EA54BD4ED1677E5A26
9A9CCD8B0E5D05F4EE77667B024844DB
0EEE9BAD07E22415439E854657FA1366
8F4E8B680D3E8D3F5AC39BD72882F713

Malicious library: install.res.1033.dll

5F96C04E3AFAE97017B201BE112284D2
73BEAD922109A61E5F9F85771A7812C5
EDFF4F58722C93D7C09ED71899416396
83601C3D4ED28E8D2BE1B99BEB8EC18C
695E794631EF130583368770E7B81E98
83601C3D4ED28E8D2BE1B99BEB8EC18C
1E6A5C7B620D487D0CFC6874C3B77C90
54025CE2A9405039899FE99A1D77E0BB
BD05FCF80E493CF9AA71EC510319469D
999A63730C9634481D1D76955A2E76A8
479BD3BB617B39CD4A46D0768A2592D4
776DFD3DF9C04BB9FCDD6C1880C3761A
8E4C57358A66EB14D31ABB614DDC68DE
A40D3AEB0DAE5B00BDB3A517F3135BBB
A85A5BFDCB7C65AB93043B8CF9E20065
01325880EFFFEC546F59490089A3B415

AsyncRAT C2

mora1987[.]work[.]gd

Fake websites addresses

ds4windows[.]io
direct-download[.]giize[.]com
tmodloader[.]org
tmodloader[.]app
ds4windows[.]net
losslessscaling[.]app
processhacker[.]dev
steamtools[.]pro
dnsjumper[.]app
free-download[.]camdvr[.]org
defendercontrol[.]org
dns-jumper[.]com
cpuz[.]app
processhacker[.]org
processhacker[.]app
steamtools[.]cc
cpuz[.]pro
wallpaper-engine[.]app
processhacker[.]net
antimicrox[.]net
defendercontrol[.]app
tmodloader[.]pro
dnsjumper[.]io
bandicam[.]app
mgba[.]app
dnsjumper[.]pro
ferdium[.]app
ds4windows[.]pro
lossless-scaling[.]online
defender-control[.]com
gom-player[.]app
defendercontrol[.]pro
lossless-scaling[.]download
antimicrox[.]pro
mgba[.]pro
lossless-scaling[.]app
losslessscaling[.]pro
mgba[.]dev
tmodloader[.]download
tmod-loader[.]com
defendercontrol[.]download
ferdium[.]pro
deadreset[.]com
gom-player[.]net
crosshairx[.]pro
libreoffice[.]pro
studioobs[.]com
studio-obs[.]net
crosshairxv2[.]com
km-player[.]com
corel-draw[.]net
glary-utilities[.]com
download-full-version[.]ooguy[.]com
crosshair-x[.]com
kms-tools[.]com
studio-obs[.]com
crosshairx[.]net
clair-obscur-33[.]com
vlc-player[.]net
arksurvival-ascended[.]com
elden-ringnightreign[.]com
ready-ornot[.]com
arma-reforger[.]com
crusader-kings[.]com
crosshairx2[.]com
mediaplayerclassic[.]net
bandizip[.]pro
obs-studio[.]site
ovr-advanced-settings[.]com
studio-obs[.]pro
vlc-media[.]com
clair-obscur-33[.]town
ovr-toolkit[.]com
crusader-kings[.]church
bandizip[.]net
apexlegends[.]org
obs-studio[.]pro
vlc-media[.]net
crosshairx[.]site
monster-hunterwilds[.]com
km-player[.]pro
mediaplayerclassic[.]pro
kms-tools[.]net
fernbus-simulator[.]com
studioobs[.]pro
bandicam[.]cc
crystaldiskmark[.]cc
crystaldiskmark[.]io
crystaldiskmark[.]dev
crystaldiskmark[.]app
crystaldiskmark[.]pro
bandicam[.]io

Fake domain infrastructure

fileget.loseyourip[.]com
file-download-crosshairx.giize[.]com
all-toll-free.loseyourip[.]com
mpc-update.giize[.]com
all-toll-free.publicvm[.]com
198.23.185[.]81
direct-download.giize[.]com

ScreenConnect C2

servermanagemen[.]xyz
185.254.97[.]249
r.manage-server[.]xyz
45.145.41[.]205
winservec[.]net
manageserver[.]xyz
cloudsynn[.]com
pingserv[.]pro
ehostservers[.]xyz
serverdnsplan[.]net
pingpanl[.]pro
managedevice[.]xyz
edgeserv[.]ru