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Detects c# red/black-team tools via typelibguid

yara LOW Yara-Rules
communitynet_guid
This rule was pulled from an open-source repository and enriched with AI. Validate in a test environment before deploying to production.
View original rule at Yara-Rules →
Retrieved: 2026-07-19T23:00:00Z · Confidence: medium

Hunt Hypothesis

This hypothesis posits that adversaries are deploying C#-based Red and Black team tools within the environment to establish persistence or conduct reconnaissance, identifiable by unique TypeLibGUID artifacts in process execution logs. The SOC team should proactively hunt for these specific GUIDs in Azure Sentinel to distinguish legitimate security tooling from malicious activity masquerading as standard administrative utilities, thereby reducing false positives and enhancing visibility into internal threat operations.

YARA Rule

rule HKTL_NET_GUID_CsharpAmsiBypass {
    meta:
        description = "Detects c# red/black-team tools via typelibguid"
        reference = "https://github.com/WayneJLee/CsharpAmsiBypass"
        author = "Arnim Rupp"
        date = "2020-12-13"
    strings:
        $typelibguid0 = "4ab3b95d-373c-4197-8ee3-fe0fa66ca122" 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:

This rule contains 1 string patterns in its detection logic.

References

False Positive Guidance

Here are 4 specific false positive scenarios for the rule “Detects C# Red/Black-Team Tools via TypelibGUID”, along with suggested filters or exclusions:

Original source: https://github.com/Yara-Rules/rules/blob/main/malware/TOOLKIT_Redteam_Tools_by_GUID.yar