heistenberg pos

Hunt Hypothesis

This detection identifies Heisenberg POS malware activity by monitoring for specific file execution patterns and memory artifacts defined in the YARA signature. Proactively hunting for this behavior in Azure Sentinel is critical to uncover early-stage point-of-sale compromises that may evade standard alerting due to their low severity classification, ensuring timely containment before data exfiltration occurs.

YARA Rule

rule heistenberg_pos
{
meta:
	author = "@patrickrolsen"
	reference = "POS Malware"
strings:
	$s1 = "KARTOXA"
	$s2 = "dmpz.log"
	$s3 = "/api/process.php?xy="
	$s4 = "User-Agent: PCICompliant" // PCICompliant/3.33
	$s6 = "%s:*:Enabled:%s"
condition:
	uint16(0) == 0x5A4D and 3 of ($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 5 string patterns in its detection logic.

References

• POS Malware
• Source Rule

False Positive Guidance

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

• Scenario: Automated Inventory Synchronization via PowerShell

  • Context: The Heisenberg malware often mimics legitimate inventory management tools. In a retail environment, scheduled tasks running PowerShell scripts to sync stock levels between the Point of Sale (POS) database and the ERP system may trigger this rule if they utilize specific API calls or file I/O patterns similar to the malware’s behavior.
  • Filter/Exclusion: Create an exclusion for processes originating from the specific scheduled task path: C:\Windows\System32\Tasks\RetailInventorySync. Additionally, filter out events where the parent process is svchost.exe (Service Host) with the service name matching RetailDataSvc, provided the user context is a dedicated Service Account (e.g., svc_pos_sync).

• Scenario: Endpoint Protection Real-Time Scanning of POS Drivers

  • Context: Heisenberg often injects code into memory or manipulates driver files. When an enterprise endpoint protection solution like CrowdStrike Falcon or SentinelOne performs a scheduled deep scan of the C:\Program Files\NCR\POS directory, it may temporarily load and inspect legacy POS drivers (pos_driver.sys). This activity can be misidentified as the malware’s driver manipulation phase.
  • Filter/Exclusion: Exclude file access events where the initiating process is a known security scanner (e.g., FalconSensor.exe, SentinelOneAgent.exe) targeting files within the standard POS installation directory (C:\Program Files\NCR or C:\ProgramData\Verifone). Ensure the exclusion applies only to read operations (FileRead) rather than write/modify actions on driver binaries.

• **Scenario