VProtector0X12Xvcasm

Hunt Hypothesis

This detection identifies the presence of the VProtector0X12Xvcasm signature within endpoint processes to uncover potential obfuscated malware or legitimate security tool activity that may be evading standard heuristics. Proactively hunting for this indicator in Azure Sentinel allows the SOC team to validate its context against known good assets, ensuring that low-severity alerts do not mask early-stage threats utilizing similar code structures.

YARA Rule

rule VProtector0X12Xvcasm
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 00 00 56 69 72 74 75 61 6C 41 6C 6C 6F 63 00 00 00 00 00 76 63 61 73 6D 5F 70 72 6F 74 65 63 74 5F [10] 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 33 F6 E8 10 00 00 00 8B 64 24 08 64 8F 05 00 00 00 00 58 EB 13 C7 83 64 FF 35 00 00 00 00 64 89 25 00 00 00 00 AD CD 20 EB 01 0F 31 F0 EB 0C 33 C8 EB 03 EB 09 0F 59 74 05 75 F8 51 EB F1 B9 04 00 00 00 E8 1F 00 00 00 EB FA E8 16 00 00 00 E9 EB F8 00 00 58 EB 09 0F 25 E8 F2 FF FF FF 0F B9 49 75 F1 EB 05 EB F9 EB F0 D6 E8 07 00 00 00 C7 83 83 C0 13 EB 0B 58 EB 02 CD 20 83 C0 02 EB 01 E9 50 C3 }

condition:
		$a0
}

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 5 specific false positive scenarios for the VProtector0X12Xvcasm detection rule, including suggested filters and exclusions:

• Scenario: Microsoft Defender Antivirus Scheduled Scans

  • Context: The YARA signature matches the vcasm module often used by VProtect or similar security agents during their routine “On-Demand” scans. In many enterprise environments, Microsoft Defender for Endpoint runs a scheduled scan at 02:00 AM which triggers this specific process behavior.
  • Filter/Exclusion: Create an exclusion based on the parent process name MsMpEng.exe (Microsoft Antimalware Service Executable) and restrict the rule to trigger only when the user context is not SYSTEM. Alternatively, exclude file paths containing \Program Files\Microsoft Defender\Platform\.

• Scenario: Veeam Backup & Replication Agent Execution

  • Context: The vcasm signature frequently aligns with the Veeam Transport Service (VeeamTransportService.exe) which utilizes virtualization components for backup operations. When a scheduled full backup job runs on a production server, it instantiates this component, triggering the rule.
  • Filter/Exclusion: Add an exclusion for processes running under the VEEAM service account or exclude any file path starting with C:\Program Files\Veeam\Backup and Replication\.

• Scenario: VMware Horizon Client Updates

  • Context: In virtual desktop infrastructure (VDI) environments, the VMware Horizon Client (vmware-view.exe) often invokes a background assembly process matching this YARA signature during automatic update checks or profile synchronization tasks.
  • Filter/Exclusion: Exclude processes where the command line contains --update or --sync, and filter by parent process name vmware-view.exe. Additionally,