PapaAlfa

Hunt Hypothesis

This hypothesis posits that adversaries are utilizing specific file signatures identified by the PapaAlfa YARA rule to establish initial footholds or execute lateral movement within the environment. The SOC team should proactively hunt for these indicators in Azure Sentinel to validate their presence across endpoints and correlate them with other low-severity alerts, ensuring early detection of stealthy threats before they escalate into critical incidents.

YARA Rule

rule PapaAlfa
{
	meta:
		copyright = "2015 Novetta Solutions"
		author = "Novetta Threat Research & Interdiction Group - [email protected]"

	strings:
		$ = "pmsconfig.msi" wide
		$ = "pmslog.msi" wide
		$ = "%sd.e%sc n%ssh%srewa%s ad%s po%sop%sing T%s %d"
		$ = "CreatP2P Thread" wide
		$ = "GreatP2P Thread" wide
	condition:
		3 of them
}

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
• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the PapaAlfa detection rule in an enterprise environment, along with suggested filters or exclusions:

• Endpoint Protection Scanning Cycles

  • Scenario: The YARA rule may trigger when the enterprise endpoint protection suite (e.g., CrowdStrike Falcon, SentinelOne, or Microsoft Defender for Endpoint) performs its scheduled background scan. These agents often spawn temporary processes that load signature databases or analyze memory regions, mimicking the behavior patterns PapaAlfa is designed to detect.
  • Filter/Exclusion: Exclude process paths containing the vendor’s installation directory (e.g., C:\Program Files\Microsoft Defender* or C:\ProgramData\SentinelOne\) and filter for known benign parent processes like MsMpEng.exe, SentinelAgent.exe, or CrowdStrikeService.exe.

• Software Deployment via Configuration Management

  • Scenario: During patch Tuesday or application rollout, configuration management tools such as Microsoft SCCM (Configuration Manager), Ivanti, or Ansible Tower execute scripts to deploy updates. These tools frequently inject code into memory or create temporary executable artifacts that match the PapaAlfa signature logic before cleaning up.
  • Filter/Exclusion: Create an exclusion based on the parent process name and command line arguments containing specific deployment tags (e.g., ccmexec.exe, Ansible-Runner, or IvantiAgent). Additionally, exclude file paths located in temporary staging folders like C:\Windows\CCMCache or C:\ProgramData\Ivanti.

• Automated Backup and Snapshot Operations

  • Scenario: Enterprise backup solutions like Veeam Backup & Replication, Commvault, or AWS Backup Agents often run scheduled jobs that mount virtual disks, read