Detects c# red/black-team tools via typelibguid

Hunt Hypothesis

This detection identifies adversary activity by monitoring for specific TypeLibGUIDs associated with known C# red and blue team tools that often indicate reconnaissance or post-exploitation tooling within the Azure environment. Proactively hunting for these signatures allows the SOC team to distinguish between legitimate administrative actions and potential threat actor presence, enabling early intervention before attackers fully establish their foothold.

YARA Rule

rule HKTL_NET_GUID_IronKit {
    meta:
        description = "Detects c# red/black-team tools via typelibguid"
        reference = "https://github.com/nshalabi/IronKit"
        author = "Arnim Rupp"
        score = 50
        date = "2020-12-13"
    strings:
        $typelibguid0 = "68e40495-c34a-4539-b43e-9e4e6f11a9fb" ascii nocase wide
        $typelibguid1 = "641cd52d-3886-4a74-b590-2a05621502a4" 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/nshalabi/IronKit
• Source Rule

False Positive Guidance

Here are 5 specific false positive scenarios for the rule “Detects c# red/black-team tools via typelibguid”, including suggested filters and exclusions:

• Scenario: Scheduled Backup or Monitoring Agents

  • Context: Enterprise backup solutions (e.g., Veeam, Commvault) or monitoring agents (e.g., SolarWinds, Datadog) often utilize C# libraries that register specific TypeLibGUIDs during their scheduled maintenance windows. These tools may trigger the rule when they initialize or update their COM components on endpoint machines.
  • Filter/Exclusion: Create an exclusion based on the ProcessName and CommandLine. Exclude processes matching known backup agent executables (e.g., Veeam.Backup.Service.exe, SolarWinds.Agent.exe) running under the context of a specific service account (e.g., DOMAIN\BackupSvc).

• Scenario: Microsoft Office 365 Click-to-Run Updates

  • Context: The Microsoft Office Click-to-Run update mechanism (OfficeClickToRun.exe or MsiExec.exe) frequently interacts with C# assemblies to manage add-ins and updates. When the update service runs, it may register or query TypeLibGUIDs associated with Office automation libraries, mimicking the behavior of Red/Black team tools.
  • Filter/Exclusion: Filter out events where the ParentProcessName is OfficeClickToRun.exe or MsiExec.exe and the Path contains \Microsoft Office\. Additionally, exclude specific known TypeLibGUIDs associated with standard Office automation libraries (e.g., 000209FF-0000-0000-C000-000000000046).

• Scenario: IT Admin PowerShell Scripts for Configuration Management