Detects c# red/black-team tools via typelibguid

Hunt Hypothesis

This detection identifies adversary activity involving C#-based Red and Blue team tools by analyzing unique TypeLibGUID artifacts often left during reconnaissance or post-exploitation phases. Proactively hunting for these signatures in Azure Sentinel is critical to distinguish legitimate security operations from malicious tooling that may be masquerading as standard administrative processes within the environment.

YARA Rule

rule HKTL_NET_GUID_HastySeries {
    meta:
        description = "Detects c# red/black-team tools via typelibguid"
        reference = "https://github.com/obscuritylabs/HastySeries"
        author = "Arnim Rupp"
        date = "2020-12-13"
    strings:
        $typelibguid0 = "8435531d-675c-4270-85bf-60db7653bcf6" ascii nocase wide
        $typelibguid1 = "47db989f-7e33-4e6b-a4a5-c392b429264b" ascii nocase wide
        $typelibguid2 = "300c7489-a05f-4035-8826-261fa449dd96" ascii nocase wide
        $typelibguid3 = "41bf8781-ae04-4d80-b38d-707584bf796b" ascii nocase wide
        $typelibguid4 = "620ed459-18de-4359-bfb0-6d0c4841b6f6" ascii nocase wide
        $typelibguid5 = "91e7cdfe-0945-45a7-9eaa-0933afe381f2" ascii nocase wide
        $typelibguid6 = "c28e121a-60ca-4c21-af4b-93eb237b882f" ascii nocase wide
        $typelibguid7 = "698fac7a-bff1-4c24-b2c3-173a6aae15bf" ascii nocase wide
        $typelibguid8 = "63a40d94-5318-42ad-a573-e3a1c1284c57" ascii nocase wide
        $typelibguid9 = "56b8311b-04b8-4e57-bb58-d62adc0d2e68" 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 10 string patterns in its detection logic.

References

• https://github.com/obscuritylabs/HastySeries
• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the Detects c# red/blue-team tools via typelibguid rule, tailored for an enterprise environment:

• Automated Patch Management Deployment

  • Scenario: The organization uses Microsoft Endpoint Configuration Manager (MECM/SCCM) or Ansible to push updates. During a scheduled maintenance window, the deployment agent executes C#-based PowerShell scripts that instantiate COM objects to verify .NET framework versions on endpoints. These actions generate typelibguid events matching known red/blue team signatures (e.g., specific GUIDs associated with Microsoft’s testing frameworks).
  • Filter/Exclusion: Create an exclusion rule for the specific process names of the deployment agents (e.g., ccmexec.exe, Ansible-Runner.exe) running under the system account (NT AUTHORITY\SYSTEM), or whitelist the specific typelibguid values associated with the patching framework.

• Enterprise Antivirus Real-Time Scanning

  • Scenario: The endpoint protection suite (e.g., CrowdStrike Falcon, Trend Micro, or Carbon Black) performs deep heuristic scanning using C# components to analyze memory structures. When these tools scan large file repositories or perform behavioral monitoring, they load specific type libraries that trigger the rule’s detection logic, mimicking the footprint of a red team reconnaissance tool.
  • Filter/Exclusion: Exclude processes belonging to the known antivirus vendor (e.g., FalconSensor.exe, TmAgent.exe) and their child processes. Additionally, filter out events originating from the specific service accounts used by the security suite (e.g., Local Service or a dedicated AntivirusService account).

• CI/CD Pipeline Artifact Validation

  • Scenario: In a DevOps environment, build servers running Jenkins, **Azure Dev