Detects c# red/black-team tools via typelibguid

Hunt Hypothesis

This rule identifies the execution of specialized C# Red and Black team tools by monitoring unique typelibguid values often associated with advanced security testing frameworks. Proactively hunting for these artifacts in Azure Sentinel is essential to distinguish legitimate internal security exercises from potential adversary activity that mimics trusted tooling to evade standard detection baselines.

YARA Rule

rule HKTL_NET_GUID_GadgetToJScript {
    meta:
        description = "Detects c# red/black-team tools via typelibguid"
        reference = "https://github.com/med0x2e/GadgetToJScript"
        author = "Arnim Rupp"
        date = "2020-12-13"
    strings:
        $typelibguid0 = "af9c62a1-f8d2-4be0-b019-0a7873e81ea9" ascii nocase wide
        $typelibguid1 = "b2b3adb0-1669-4b94-86cb-6dd682ddbea3" 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 2 string patterns in its detection logic.

References

• https://github.com/med0x2e/GadgetToJScript
• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the rule “Detects c# red/blue-team tools via typelibguid” in an enterprise environment, along with suggested filters or exclusions:

• Scheduled Software Deployment (SCCM/MECM)

  • Scenario: The System Center Configuration Manager (SCCM) client service (ccmexec.exe) runs a scheduled task to deploy Microsoft Office updates. During the installation phase, it invokes C#-based deployment agents that register COM type libraries, triggering the typelibguid detection on endpoints across the domain.
  • Filter/Exclusion: Exclude processes where the parent process is ccmexec.exe or WuaAgent.exe, and the command line contains keywords like “Microsoft Office,” “Deployment,” or specific SCCM package IDs (e.g., *PackageID=*).

• Automated Patch Management via WSUS

  • Scenario: A nightly job runs on domain-joined workstations to check for Windows Updates. The Windows Update Agent (wuauclt.exe or usocoreworker.exe) executes C# scripts to query the local update database, generating specific TypeLib GUIDs associated with the Microsoft Management Console (MMC) snap-ins used by the patching tool.
  • Filter/Exclusion: Create an exclusion for events originating from the Windows Update service context where the executable path is under C:\Windows\SoftwareDistribution\ or C:\Windows\System32\, specifically targeting known GUIDs associated with Microsoft.Update.Client.

• Enterprise Antivirus Real-Time Scanning

  • Scenario: A major endpoint protection suite (e.g., CrowdStrike Falcon, Carbon Black, or Symantec Endpoint Protection) performs a real-time scan of the local file system. The scanner’s C# module interacts with the Windows Registry to verify file signatures, inadvertently creating