Packmanv10BrandonLaCombe

Hunt Hypothesis

This YARA rule targets the Packmanv10 Brandon LaCombe variant, a known ransomware strain that typically encrypts files and establishes persistence through scheduled tasks or services. Proactively hunting for this signature allows the SOC to identify compromised endpoints early, preventing the lateral movement and data exfiltration often associated with this low-severity but high-impact threat.

YARA Rule

rule Packmanv10BrandonLaCombe
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E8 00 00 00 00 5B 8D 5B C6 01 1B 8B 13 8D 73 14 6A 08 59 01 16 AD 49 75 FA 8B E8 C6 06 E9 8B 43 0C 89 46 01 6A 04 68 00 10 00 00 FF 73 08 51 FF 55 08 8B }

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 uses the packman CLI tool (a package manager for Windows) to install or update dependencies for a C#/.NET project during a build pipeline or local development session.
  • Filter/Exclusion: Exclude processes where the parent process is dotnet.exe, msbuild.exe, vstest.console.exe, or cmd.exe/powershell.exe originating from a known development directory (e.g., C:\dev\, C:\src\, or user profile paths) and the command line contains arguments like install, update, or restore.
• Scenario: An automated CI/CD agent (e.g., Azure DevOps, Jenkins, or GitHub Actions runner) executes a build step that invokes packman to manage NuGet or custom package dependencies as part of a scheduled job or trigger-based pipeline.
  • Filter/Exclusion: Exclude events where the process is running under a service account (e.g., svc-cicd, jenkins-agent, gha-runner) or the working directory matches known CI/CD workspace paths (e.g., C:\agent\_work\, C:\jenkins\workspace\).
• Scenario: A system administrator or support engineer manually runs packman from an elevated command prompt to troubleshoot or repair a specific application’s dependencies on a jump host or management server.
  • Filter/Exclusion: Exclude if the user belongs to a privileged group (e.g., Domain Admins, Local Administrators, App Support Team) and the process is initiated from an interactive session (not a service) on a designated management or jump host inventory.
• Scenario: A legacy application installer or a custom internal tooling script uses packman as a dependency resolution step during a scheduled maintenance window (