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 signatures to establish persistence or execute reconnaissance within Azure environments. Proactively hunting for these specific identifiers in Azure Sentinel allows the SOC team to distinguish legitimate administrative activity from stealthy tool usage, ensuring early detection of potential lateral movement or post-exploitation activities even when initial alerts are low severity.

YARA Rule

rule HKTL_NET_GUID_Stracciatella {
    meta:
        description = "Detects c# red/black-team tools via typelibguid"
        reference = "https://github.com/mgeeky/Stracciatella"
        author = "Arnim Rupp"
        date = "2020-12-13"
    strings:
        $typelibguid0 = "eaafa0ac-e464-4fc4-9713-48aa9a6716fb" 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/mgeeky/Stracciatella
• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the “Detects C# Red/Black-Team Tools via TypelibGUID” rule, including suggested filters and exclusions:

• Scenario: Automated Patch Management Deployment

  • Context: Enterprise patch management solutions like Microsoft Endpoint Configuration Manager (MECM) or Ivanti frequently utilize C# components to deploy updates. During a scheduled maintenance window, these tools generate specific typelibguid entries while registering COM objects for agent communication and reporting.
  • Suggested Filter/Exclusion: Create an exclusion based on the Process Name (e.g., ccmexec.exe, IvantiAgent.exe) combined with a time-based filter to only alert outside of standard maintenance windows (e.g., 02:00–06:00 local time).

• Scenario: Development Build and CI/CD Pipelines

  • Context: In R&D departments, build servers running Jenkins, Azure DevOps, or GitLab CI often execute C# compilation tasks. When these agents invoke tools like MSBuild (msbuild.exe) or the .NET SDK to compile red-team simulation code or validate black-team security scripts, they instantiate standard .NET typelibs that match the detection signature.
  • Suggested Filter/Exclusion: Exclude alerts originating from known CI/CD Hostnames (e.g., build-server-01, jenkins-agent-*) and filter by Parent Process Name being a build orchestrator (e.g., java.exe for Jenkins or taskeng.exe for Azure DevOps).

• Scenario: Endpoint Detection and Response (EDR) Self-Scanning

  • Context: Modern EDR platforms such as CrowdStrike Falcon, SentinelOne, or **