DebuggerHiding Thread

Hunt Hypothesis

Adversaries may use debugger hiding techniques to evade detection by masking their malicious threads within legitimate processes. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify potential persistence or evasion tactics early in the attack lifecycle.

YARA Rule

rule DebuggerHiding__Thread : AntiDebug DebuggerHiding {
	meta:
	    Author = "naxonez"
		reference = "https://github.com/naxonez/yaraRules/blob/master/AntiDebugging.yara"
		weight = 1
	strings:
		$ ="SetInformationThread"
	condition:
		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

References

• https://github.com/naxonez/yaraRules/blob/master/AntiDebugging.yara
• Source Rule

False Positive Guidance

• Scenario: A system administrator is using GDB (GNU Debugger) to debug a critical application during an incident response.
  Filter/Exclusion: process.name != "gdb" or process.parent.name != "gdb"

• Scenario: A scheduled job runs a script that uses Process Monitor (ProcMon) to monitor file system activity for troubleshooting.
  Filter/Exclusion: process.name != "procmon" or process.parent.name != "procmon"

• Scenario: A developer is using Visual Studio with the debugger attached to a local process for code testing.
  Filter/Exclusion: process.name != "devenv" or process.parent.name != "devenv"

• Scenario: A security tool like Windows Defender or Microsoft Endpoint Detection and Response (EDR) is using a debugger internally to analyze suspicious processes.
  Filter/Exclusion: process.name in ("msmpeng.exe", "mfev.exe") or process.parent.name in ("msmpeng.exe", "mfev.exe")

• Scenario: A system update or patching tool like Windows Update or SCCM (System Center Configuration Manager) temporarily attaches a debugger to a process during deployment.
  Filter/Exclusion: process.name in ("svchost.exe", "wuauserv.exe", "ccmexec.exe") or process.parent.name in ("svchost.exe", "wuauserv.exe", "ccmexec.exe")