Detects c# red/black-team tools via typelibguid

Hunt Hypothesis

This hunt targets adversaries leveraging C#-based Red and Black team tools that expose unique typelibguid artifacts during execution within Azure Sentinel. Proactively hunting for these specific identifiers allows the SOC to distinguish between legitimate security operations and potential adversary reconnaissance or tool deployment activities that may otherwise be obscured by low-severity noise.

YARA Rule

rule HKTL_NET_GUID_aresskit {
    meta:
        description = "Detects c# red/black-team tools via typelibguid"
        reference = "https://github.com/BlackVikingPro/aresskit"
        author = "Arnim Rupp"
        date = "2020-12-13"
    strings:
        $typelibguid0 = "8dca0e42-f767-411d-9704-ae0ba4a44ae8" ascii nocase wide
    condition:
        (uint16(0) == 0x5A4D and uint32(uint32(0x3C)) == 0x00004550) and any of them
}

Deployment Notes

This YARA rule can be deployed in the following contexts:

• Microsoft Defender for Endpoint — Custom indicators / advanced hunting
• Email Gateway — Attachment scanning
• File Share Monitoring — Periodic scanning of shared drives
• YARA CLI — Manual threat hunting on endpoints

This rule contains 1 string patterns in its detection logic.

References

• https://github.com/BlackVikingPro/aresskit
• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the rule “Detects c# red/blue-team tools via typelibguid”, including suggested filters and exclusions:

• Scenario: Automated Compliance Scanning via Microsoft Baseline Security Analyzer (MBSA)

  • Context: Enterprise security teams often deploy scheduled tasks that run MBSA or similar .NET-based compliance scanners across the domain to check for missing patches and configuration drift. These tools utilize C# libraries that register specific typelibguid values during execution, mimicking the behavior of Red/Blue team assessment tools (like BloodHound or SharpUp).
  • Filter/Exclusion: Create an exclusion rule for processes running under the SYSTEM or a dedicated ComplianceServiceAccount context where the parent process is TaskScheduler.exe. Additionally, filter out specific known typelibguid values associated with standard Microsoft assessment frameworks (e.g., GUID-8F36E4C2...) if they are not part of your active Red/Blue tool inventory.

• Scenario: Endpoint DLP Agent Telemetry and Policy Updates

  • Context: Many Data Loss Prevention (DLP) solutions (such as Symantec DLP, McAfee Total Protection for Endpoints, or Microsoft Purview) rely on C# components to monitor file access and network traffic. During daily policy synchronization or agent health checks, these agents instantiate .NET assemblies that generate typelibguid events identical to those used by active reconnaissance tools like PowerSploit or Nmap-C#.
  • Filter/Exclusion: Exclude the specific executable paths of known DLP agents (e.g., C:\Program Files\Symantec\DLP\Agent\*) from triggering this rule. Implement a logic filter that suppresses alerts if the detected typelibguid matches the hash or signature of the organization’s approved D