This hunt targets adversaries leveraging C#-based red and black team tools that expose unique TypeLibGUID artifacts to evade standard signature-based detection. Proactively hunting for these GUIDs in Azure Sentinel is critical because they often indicate early-stage reconnaissance or post-exploitation tooling that may precede more severe lateral movement activities.
rule HKTL_NET_GUID_SharpLoginPrompt {
meta:
description = "Detects c# red/black-team tools via typelibguid"
reference = "https://github.com/shantanu561993/SharpLoginPrompt"
author = "Arnim Rupp"
date = "2020-12-13"
strings:
$typelibguid0 = "c12e69cd-78a0-4960-af7e-88cbd794af97" 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/Black-Team Tools via TypelibGUID rule, including suggested filters and exclusions:
Scenario: Automated Patch Management Deployment (SCCM/MECM)
TypelibGUID as known Red Team tools like Cobalt Strike or Empire, triggering alerts during routine patch cycles.\Microsoft\CCM\ and parent processes named ccmexec.exe. Additionally, filter out events where the command line arguments contain keywords such as /install, /update, or specific SCCM package IDs.Scenario: Scheduled Antivirus Definition Updates
TypelibGUID signatures indistinguishable from Black Team reconnaissance tools like PowerSploit or Nishang.FalconSensorService.exe, SentinelOneAgent.exe) and restrict the rule to only trigger on user-initiated sessions rather than system-level scheduled tasks (checking the LogonType or JobId fields).Scenario: Enterprise Single Sign-On (SSO) Token Refresh