VcasmProtector10

Hunt Hypothesis

This rule detects the presence of the VcasmProtector10 YARA signature, which identifies specific malicious or suspicious code patterns often associated with targeted intrusions or low-level system manipulation. Proactively hunting for this indicator in Azure Sentinel allows the SOC team to identify compromised endpoints or anomalous processes before they escalate to more severe impacts, ensuring early containment of stealthy threats.

YARA Rule

rule VcasmProtector10
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 55 8B EC 6A FF 68 [3] 00 68 [3] 00 64 A1 00 00 00 00 50 64 89 25 00 00 00 00 E8 03 00 00 00 C7 84 00 58 EB 01 E9 83 C0 07 50 C3 FF 35 E8 03 00 00 00 C7 84 00 58 EB 01 E9 83 C0 07 50 C3 FF 35 E8 07 00 00 00 C7 83 83 C0 13 EB 0B 58 EB 02 CD 20 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

• Scenario: Execution of the vcasmprotector binary during a scheduled Windows Server Update Services (WSUS) or third-party patch management cycle (e.g., SCCM, Ivanti, or Ansible) where the tool is used to verify or apply security patches to virtualized workloads.

  • Filter/Exclusion: Exclude processes where the parent process is a known patch management agent (e.g., ccmexec.exe, svchost.exe with specific service names, or ansible-playbook) and the file path matches the standard installation directory (e.g., C:\Program Files\VCASM\ or C:\Tools\VCASM\).

• Scenario: Manual execution by a DevOps engineer or System Administrator using vcasmprotector in a CI/CD pipeline (e.g., Jenkins, GitLab CI, or Azure DevOps) to validate container images or virtual machine configurations before deployment to production.

  • Filter/Exclusion: Exclude processes spawned by CI/CD agents (e.g., jenkins.exe, gitlab-runner.exe, vsts-agent.exe) or where the working directory is within a known build artifact folder (e.g., C:\jenkins\workspace\, C:\gitlab-runner\builds\).

• Scenario: Execution during a routine vulnerability scan or integrity check by a security tool like Tenable.io, Qualys, or Rapid7 InsightVM, which may invoke vcasmprotector as a helper script or binary to assess protection status on target hosts.

  • Filter/Exclusion: Exclude processes where the parent process is a known vulnerability scanner agent (e.g., tenscan.exe, qualysagent.exe, insightvm.exe) or where the command line arguments contain typical scan-related flags (e.g., --check, --status,