Detects .NET red/black-team tools via typelibguid

Hunt Hypothesis

This hunt detects adversarial use of specialized .NET-based Red and Black team tools by identifying unique typelib GUID signatures within Azure Sentinel logs. Proactively hunting for these indicators allows the SOC to distinguish legitimate security testing activities from potential malicious reconnaissance or tool deployment that mimics standard administrative behavior.

YARA Rule

rule HKTL_NET_GUID_CloneVault {
    meta:
        description = "Detects .NET red/black-team tools via typelibguid"
        reference = "https://github.com/mdsecactivebreach/CloneVault"
        author = "Arnim Rupp"
        date = "2021-01-21"
    strings:
        $typelibguid0 = "0a344f52-6780-4d10-9a4a-cb9439f9d3de" 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/mdsecactivebreach/CloneVault
• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the rule “Detects .NET red/black-team tools via typelibguid,” along with suggested filters or exclusions:

• Scenario: Microsoft Visual Studio Build Automation

  • Context: During nightly CI/CD pipelines, Visual Studio (MSBuild) compiles .NET solutions. The build process often instantiates COM objects that expose specific typelibguid values similar to those used by security assessment tools like Nmap or custom red-team agents.
  • Filter/Exclusion: Exclude processes where the executable path contains \Program Files\Microsoft Visual Studio\* and the parent process is msbuild.exe or devenv.exe.

• Scenario: Office 365 ProPlus Background Updates

  • Context: The Microsoft Office Click-to-Run service (OfficeClickToRun.exe) periodically queries .NET assemblies to manage license compliance and feature updates. This activity frequently triggers the detection logic due to shared library GUIDs used by both Office components and security tools (e.g., Cobalt Strike Beacon).
  • Filter/Exclusion: Create an exclusion for typelibguid values associated with known Office update services, specifically filtering out events where the process name is OfficeClickToRun.exe or Groove.exe.

• Scenario: Scheduled PowerShell Health Checks

  • Context: Enterprise IT teams often deploy scheduled PowerShell scripts (Task Scheduler) that utilize .NET libraries to query system health. These scripts may load assemblies with GUIDs overlapping with black-team tools like BloodHound or SharpUp, causing the rule to flag routine maintenance as a potential tool execution.
  • Filter/Exclusion: Exclude events where the parent process is svchost.exe (specifically the “Task Scheduler” service) and the command line arguments contain keywords such as -Command, -File, or specific