PackmanV10BrandonLaCombe

Hunt Hypothesis

This YARA rule targets specific memory patterns associated with the PackmanV10BrandonLaCombe signature, indicating the presence of a low-severity malware variant or script that may be executing in user space. Proactively hunting for this signature allows the SOC team to identify stealthy, low-fidelity intrusions that might evade traditional network-based detections, ensuring early containment of potential footholds within the Azure environment.

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 }

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 PowerShell module (often aliased as Install-Package) to manage NuGet packages or internal library dependencies within a CI/CD pipeline or local build environment. The YARA rule likely matches the specific string “Packman” or the module’s binary signature, triggering an alert when the script is executed.

  • Filter/Exclusion: Exclude processes where the parent process is pwsh.exe or powershell.exe and the command line contains -Command or -File with arguments referencing Install-Package, Update-Package, or Save-Package. Additionally, exclude files located in standard development directories such as C:\Users\<User>\.nuget\ or project-specific packages/ folders.

• Scenario: An IT administrator runs a scheduled maintenance task using a custom PowerShell script that leverages the Packman module to audit or update internal software components across a fleet of servers. The script is stored in a shared network location or a specific admin tools directory, and the YARA rule flags the loaded module or the script file itself.

  • Filter/Exclusion: Exclude files with the .ps1 extension located in known administrative tool directories (e.g., C:\AdminTools\, C:\Scripts\Maintenance\) or network shares mapped to the IT department. You can also filter by the specific user account (e.g., DOMAIN\svc-itadmin) or the parent process svchost.exe if the task is run as a scheduled job.

• Scenario: A security team or QA engineer uses a test harness or a custom-built “packman” utility (not the standard NuGet module) to bundle application artifacts for deployment testing. The binary or script is named packman.exe or packman.ps1 to align with internal naming conventions,