AHTeamEPProtector03faketElock061FEUERRADER

Hunt Hypothesis

This detection identifies potential endpoint protection evasion attempts where adversaries manipulate file integrity or process behavior to bypass security controls using specific YARA signatures. A proactive hunt is essential in Azure Sentinel to uncover stealthy threats that may not trigger high-severity alerts but could indicate early-stage reconnaissance or lateral movement within the environment.

YARA Rule

rule AHTeamEPProtector03faketElock061FEUERRADER
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 90 [46] 90 FF E0 E9 00 00 00 00 60 E8 00 00 00 00 58 83 C0 08 F3 EB FF E0 83 C0 28 50 E8 00 00 00 00 5E B3 33 8D 46 0E 8D 76 31 28 18 F8 73 00 C3 8B FE B9 3C 02 }

condition:
		$a0 at pe.entry_point
}

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 1 string patterns in its detection logic.

• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the detection rule AHTeamEPProtector03faketElock061FEUERRADER, along with targeted filters and exclusions:

• Scenario: Scheduled Antivirus Database Updates

  • Context: The enterprise endpoint protection suite (e.g., Microsoft Defender, CrowdStrike Falcon) performs nightly signature updates. During this process, the update service often spawns temporary worker threads that mimic the behavior of a “fake” lock or encryption routine to prevent file access conflicts during the download and installation phase.
  • Filter/Exclusion: Create an exclusion based on the Process Name (MpCmdG.exe for Defender, CnsNotify.exe for CrowdStrike) combined with a specific Command Line argument containing keywords like /update, /scan, or /install. Alternatively, exclude the specific update service account (e.g., NT SERVICE\DefenderSvc) from triggering this rule.

• Scenario: Enterprise Backup and Archiving Jobs

  • Context: Automated backup solutions such as Veeam Agent for Microsoft Windows or Acronis Cyber Protect run scheduled jobs to archive user data. These tools frequently lock files in the C:\Users directory while compressing them, which can trigger the “fake lock” detection logic if the YARA rule interprets the compression locking mechanism as a potential ransomware encryption pattern.
  • Filter/Exclusion: Exclude processes belonging to known backup vendors by adding their executable paths (e.g., C:\Program Files\Veeam\Agent\vagent.exe or C:\Program Files\Acronis\Cyber Protect\Engine\engine.exe) to the rule’s exclusion list. Additionally, filter out events occurring during defined maintenance windows (e.g., 02:00 – 04:00 local time).

• **Scenario: