PEncryptv10

Hunt Hypothesis

This hypothesis targets the execution of PEncryptv10, a known password cracker and recovery tool, which adversaries may deploy to extract or brute-force credentials from local password stores. Proactively hunting for this indicator in Azure Sentinel allows the SOC team to identify potential post-compromise credential theft activities that often precede lateral movement or privilege escalation within the environment.

YARA Rule

rule PEncryptv10
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 9C BE 00 10 40 00 8B FE B9 28 03 00 00 BB 78 56 34 12 AD 33 C3 AB E2 FA 9D 61 }

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

• Scenario: A developer or DevOps engineer manually runs the penv (or similar PEncrypt-based) utility from a command line to encrypt a configuration file or secret before committing it to a repository or transferring it to a staging environment.
  • Filter/Exclusion: Exclude executions where the parent process is a standard shell (cmd.exe, powershell.exe, bash.exe) and the command line arguments contain specific encryption flags (e.g., -e, --encrypt) or reference file extensions like .pem, .key, or .cfg.
• Scenario: A CI/CD pipeline (e.g., Jenkins, Azure DevOps, GitHub Actions) executes a build step that invokes the PEncrypt tool to encrypt artifacts or secrets as part of a scheduled job or webhook-triggered workflow.
  • Filter/Exclusion: Exclude executions where the parent process is a CI/CD agent (e.g., jenkins-agent.exe, azure-devops-agent.exe, github-actions-runner.exe) or where the working directory path contains typical CI/CD workspace identifiers (e.g., workspace, builds, artifacts).
• Scenario: An automated backup or archival script uses PEncrypt to encrypt large data dumps or log files before moving them to long-term storage, often triggered by a Windows Task Scheduler job.
  • Filter/Exclusion: Exclude executions where the parent process is Task Scheduler (svchost.exe with specific task parameters) or schtasks.exe, and the target file path ends with common archive extensions (.zip, .tar.gz, .bak) or is located in a designated backup directory (e.g., C:\Backups, D:\Archive).
• Scenario: A specialized security tool or compliance scanner (e.g., a custom internal audit script) uses PEncrypt to encrypt evidence files or configuration snapshots during a