DingBoysPElockv007

Hunt Hypothesis

This detection identifies potential execution of malicious PE files associated with the DingBoy malware family, which often utilizes packing or locking mechanisms to evade static analysis. Proactively hunting for this behavior in Azure Sentinel is essential to uncover early-stage infections that may be missed by signature-only defenses, allowing analysts to investigate lateral movement before the adversary establishes a persistent foothold.

YARA Rule

rule DingBoysPElockv007
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 57 56 52 51 53 E8 00 00 00 00 5D 8B D5 81 ED 23 35 40 00 }

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 5 specific false positive scenarios for the DingBoysPElockv007 detection rule, along with recommended filters and exclusions:

• Scenario: Legitimate execution of Microsoft Office Click-to-Run updates.

  • Context: The OfficeClickToRun.exe process frequently locks PE (Portable Executable) headers during background update cycles to prevent file corruption while downloading new patches. This behavior mimics the locking mechanism targeted by the DingBoys rule.
  • Filter/Exclusion: Exclude processes where the command line contains OfficeClickToRun.exe and the parent process is Microsoft Office Click-to-Run Service. Add a filter to ignore events originating from the path C:\Program Files\Microsoft Office\root\Office16\.

• Scenario: Scheduled Antivirus definition updates via Windows Defender.

  • Context: During scheduled maintenance windows, MpCmdG.exe (Windows Defender) locks PE files within its installation directory to apply new virus definitions. The YARA rule may misinterpret this high-volume file locking as a malicious PE lock attempt by DingBoys.
  • Filter/Exclusion: Create an exclusion for the process name MpCmdG.exe when the user context is NT AUTHORITY\SYSTEM. Additionally, exclude events occurring between 02:00 and 04:00 local time on weekdays to align with standard maintenance schedules.

• Scenario: Enterprise Endpoint Protection (e.g., CrowdStrike) real-time scanning.

  • Context: The Cfnetwork.exe or CsAgent.exe processes from CrowdStrike Falcon actively lock PE headers of critical system binaries during real-time heuristic scans to ensure integrity checks do not conflict with active file handles.
  • Filter/Exclusion: Exclude all events where the process image path starts with `C:\Program