PELockNTv202c

Hunt Hypothesis

This YARA rule targets specific characteristics of the PELockNTv202c malware, a variant of the LockBit ransomware family, indicating the presence of a high-impact threat actor capable of deploying sophisticated encryption payloads. Proactively hunting for this signature allows the SOC to identify early-stage infections or dormant payloads within Azure environments before the ransomware can propagate and encrypt critical data.

YARA Rule

rule PELockNTv202c
{
      meta:
		author="malware-lu"
strings:
		$a0 = { EB 02 C7 85 1E EB 03 CD 20 EB EB 01 EB 9C EB 01 EB EB 02 CD }

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

• Legitimate Antivirus/EDR Self-Update or Quarantine Operations: When enterprise EDR agents (e.g., CrowdStrike Falcon, Microsoft Defender for Endpoint) or AV solutions (e.g., Symantec Endpoint Protection) perform background updates or process quarantine actions, they may temporarily lock or modify PE headers to prevent tampering, potentially matching the PELockNTv202c signature if it targets specific locking mechanisms or header anomalies.

  • Filter/Exclusion: Exclude processes originating from known EDR/AV service executables (e.g., FalconSensor.exe, MsMpEng.exe, SymantecSvc.exe) and their child processes. Additionally, exclude files located in standard AV/EDR installation directories (e.g., C:\Program Files\CrowdStrike\, C:\Program Files\Microsoft Defender\).

• Software Deployment via Group Policy or SCCM: During mass software deployments using System Center Configuration Manager (SCCM) or Group Policy Preferences, installation packages (MSI/EXE) may be staged in temporary directories (%TEMP%, C:\Windows\Temp) or application data folders. Some installers use custom PE locking or header modification techniques to ensure integrity during extraction, which can trigger this rule on the staged binaries.

  • Filter/Exclusion: Exclude files created by known deployment services (e.g., CCMSetup.exe, msiexec.exe with specific command-line arguments related to GPO) and files residing in standard temporary or staging directories (C:\Windows\Temp\, %LOCALAPPDATA%\Temp\) that are less than 24 hours old.

• Legacy Application Compatibility Shims: Older enterprise applications (e.g., legacy Java apps, .NET Framework 2.0/3.5 apps, or specific vendor tools like Oracle Database clients) may use compatibility shims or custom