blackpos v2

Hunt Hypothesis

This detection identifies potential Point of Sale (POS) malware activity by leveraging the BlackPOS V2 YARA signature to scan for known malicious artifacts within endpoint telemetry. Proactively hunting for this behavior in Azure Sentinel is critical because early identification of these low-severity indicators allows the SOC team to validate and contain stealthy financial data theft before it escalates into a significant breach.

YARA Rule

rule blackpos_v2
{
meta:
	author = "@patrickrolsen"
	version = "0.1"
	reference = "http://blog.nuix.com/2014/09/08/blackpos-v2-new-variant-or-different-family"
strings:
	$s1 = "Usage: -[start|stop|install|uninstall"
	$s2 = "\\SYSTEM32\\sc.exe config LanmanWorkstation"
	$s3 = "t.bat"
	$s4 = "mcfmisvc"
condition:
	uint16(0) == 0x5A4D and all of ($s*)
}

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 4 string patterns in its detection logic.

References

• http://blog.nuix.com/2014/09/08/blackpos-v2-new-variant-or-different-family
• Source Rule

False Positive Guidance

Here are 4 specific false positive scenarios for the blackpos v2 detection rule in an enterprise environment, including suggested filters and exclusions:

• Scenario: Automated Endpoint Patching via SCCM/Intune

  • Context: The System Center Configuration Manager (SCCM) or Microsoft Intune agent executes a scheduled task to deploy security updates. This process often involves writing executable payloads to temporary directories, modifying the HKLM\Software registry keys, and creating new service entries that mimic the behavior of POS malware installing drivers or services.
  • Filter/Exclusion: Create an exclusion for processes running under the System account with a parent process of ccmexec.exe (SCCM) or Microsoft.IngestionService.exe (Intune). Specifically, filter out file creation events where the source path is within %TEMP% or C:\Windows\CCMCache.

• Scenario: Antivirus Real-Time Scanning and Quarantine Operations

  • Context: Enterprise-grade AV solutions like CrowdStrike Falcon or SentinelOne frequently scan executable files in real-time. When a file is flagged for deep inspection, the AV engine may inject code into running processes or create temporary quarantine copies with similar hash signatures to legitimate binaries, triggering the YARA rule’s memory injection or file modification logic.
  • Filter/Exclusion: Exclude events where the parent process name matches known AV engines (e.g., csfalcon.exe, S1Service.exe, MsMpEng.exe). Additionally, filter out file operations occurring in standard quarantine directories such as C:\ProgramData\CrowdStrike\ or C:\Windows\System32\catroot2.

• Scenario: IT Admin Performing Legacy POS Driver Updates

  • Context: During maintenance windows, IT administrators manually install or update drivers for legacy Point-of-Sale hardware (e