Detects c# red/black-team tools via typelibguid

Hunt Hypothesis

This hunt hypothesis posits that adversaries are leveraging C#-based red and black team tools within the environment, identifiable by unique typelibguid artifacts often associated with legitimate security utilities. Proactively hunting for these specific GUIDs in Azure Sentinel is critical to distinguish between authorized defensive tooling and potential adversary persistence mechanisms masquerading as standard administrative software.

YARA Rule

rule HKTL_NET_GUID_AllTheThings {
    meta:
        description = "Detects c# red/black-team tools via typelibguid"
        reference = "https://github.com/johnjohnsp1/AllTheThings"
        author = "Arnim Rupp"
        date = "2020-12-13"
    strings:
        $typelibguid0 = "0547ff40-5255-42a2-beb7-2ff0dbf7d3ba" 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/johnjohnsp1/AllTheThings
• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the rule “Detects C# Red/Black-Team Tools via TypelibGUID”, along with suggested filters or exclusions:

• Scenario: Automated Build and Deployment Pipelines

  • Context: CI/CD agents (e.g., Jenkins, Azure DevOps, GitHub Actions) running on build servers frequently execute C# compilation tasks (csc.exe) or deployment scripts that instantiate .NET assemblies with specific TypeLib GUIDs. These tools often mimic the behavior of red-team utilities like SharpChk or PowerShell Empire agents during the build process.
  • Suggested Filter: Exclude processes where the parent executable is a known CI/CD runner (e.g., java.exe, node.exe, dotnet.exe) and the command line contains flags related to build artifacts (e.g., /t:Build, -p:Configuration=Release).

• Scenario: Enterprise Endpoint Management Software

  • Context: System administration tools such as Microsoft SCCM (ConfigMgr), Ivanti, or Jamf often deploy C# agents that perform inventory scans or patch management. These agents utilize standard .NET libraries to interact with the OS, generating TypeLib GUIDs identical to those used by black-team reconnaissance tools like SharpHunt or BloodHound.
  • Suggested Filter: Create an exclusion for specific process paths located in known enterprise management directories (e.g., C:\Program Files\Microsoft SCCM\Agent, C:\Program Files\Ivanti) and restrict the rule to only trigger on processes launched from user home directories or temporary folders (%TEMP%).

• Scenario: Scheduled Microsoft Office Macro Execution

  • Context: In environments with heavy Excel usage, scheduled tasks often launch excel.exe which loads VBA macros written in C# or COM add