Petitevafterv14

Hunt Hypothesis

This detection identifies potential malicious activity associated with the Petitevafterv14 signature, which may indicate early-stage file-based threats or specific malware variants within the environment. Proactively hunting for this signal in Azure Sentinel allows the SOC team to validate low-severity alerts before they escalate, ensuring rapid identification of subtle indicators that might otherwise be overlooked during routine monitoring.

YARA Rule

rule Petitevafterv14
{
      meta:
		author="malware-lu"
strings:
		$a0 = { B8 [4] 66 9C 60 50 8D [5] 68 [4] 83 }

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 3-5 specific false positive scenarios for the Petitevafterv14 detection rule, formatted with suggested filters and exclusions:

• Scenario: Legitimate execution of Microsoft Defender Antivirus (MSRT) updates or scheduled scans.

  • Context: The YARA rule may flag the MsMpEng.exe process when it loads specific update signatures that match the Petitevafterv14 signature pattern, particularly during off-hours maintenance windows.
  • Suggested Filter/Exclusion: Exclude processes where the executable path matches C:\Program Files\Windows Defender\MsMpEng.exe and the parent process is svchost.exe (specifically the Wuauserv service).

• Scenario: Deployment of Sysinternals Process Monitor or Process Explorer by IT Administrators.

  • Context: During routine troubleshooting, administrators often run these tools to analyze system behavior. The rule might trigger when these tools interact with specific DLLs or registry keys that resemble the Petitevafterv14 artifact structure.
  • Suggested Filter/Exclusion: Create a whitelist for executable paths containing C:\Program Files\Sysinternals\ (e.g., ProcMon.exe, procexp64.exe) and exclude events where the user context is a member of the “Domain Admins” or “IT_Ops” security group.

• Scenario: Execution of Ansible or Puppet automation agents performing configuration management tasks.

  • Context: Configuration management tools frequently inject scripts or modify system files in ways that mimic the behavioral patterns detected by Petitevafterv14, especially when deploying updates to endpoint security policies.
  • Suggested Filter/Exclusion: Exclude events where the parent process is ansible-runner.exe (or puppet-agent)