This hunt targets adversaries leveraging C#-based red and black team tools that expose unique typelibguid artifacts to establish persistence or conduct reconnaissance within the environment. Proactively hunting for these specific identifiers in Azure Sentinel is critical because their presence often signals advanced tool deployment that may bypass standard signature-based detections, requiring manual validation to distinguish between authorized security operations and malicious activity.
rule HKTL_NET_GUID_Dropless_Malware {
meta:
description = "Detects c# red/black-team tools via typelibguid"
reference = "https://github.com/NYAN-x-CAT/Dropless-Malware"
author = "Arnim Rupp"
date = "2020-12-13"
strings:
$typelibguid0 = "23b739f7-2355-491e-a7cd-a8485d39d6d6" ascii nocase wide
condition:
(uint16(0) == 0x5A4D and uint32(uint32(0x3C)) == 0x00004550) and any of them
}
This YARA rule can be deployed in the following contexts:
This rule contains 1 string patterns in its detection logic.
Here are 4 specific false positive scenarios for the Detects c# red/blue-team tools via typelibguid rule in an enterprise environment, along with suggested mitigations:
Scenario: Automated Patch Management Deployment
typelibguid entries associated with .NET framework components used for system state analysis.C:\Program Files\Microsoft Configuration Manager\bin\x64\) and restrict the rule to trigger only when the parent process is not ccmexec.exe or IvAntiAgent.exe.Scenario: Scheduled Backup Verification Jobs
typelibguid values identical to those used by security testing frameworks during their initial handshake.typelibguid hashes associated with the backup vendor’s known C# libraries.Scenario: Enterprise Single Sign-On (SSO) Token Refresh