ACProtectV13Xrisco

Hunt Hypothesis

This rule detects the presence of ACProtect v13 packed executables, a common obfuscation technique used by adversaries to hide malicious payloads and evade static analysis. Proactively hunting for these artifacts in Azure Sentinel helps identify potentially compromised endpoints or staging areas where attackers may be using packed binaries to maintain persistence or execute stealthy operations.

YARA Rule

rule ACProtectV13Xrisco
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 50 E8 01 00 00 00 75 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

• Legacy Application Updates via Silent Installers: Many older enterprise applications (e.g., specific versions of Adobe Creative Suite, older Oracle Java, or proprietary ERP clients) use ACProtect v1.3 to protect their installer executables (setup.exe or install.exe) to prevent tampering. When these updates are deployed via SCCM or Intune, the protected binary is written to disk and executed, triggering the YARA signature.

  • Filter/Exclusion: Exclude files located in standard installation directories (e.g., C:\Program Files\, C:\Program Files (x86)\) or specific known paths like C:\Windows\Installer\ if the file name matches known legacy installer patterns (e.g., *setup.exe, *install.exe) and the parent process is a known deployment agent (e.g., ccmexec.exe, msiexec.exe).

• Third-Party Antivirus/Security Tool Self-Updates: Some niche or older security tools, or specific driver update packages from hardware vendors (e.g., certain Realtek or Intel drivers), may package their update binaries using ACProtect v1.3. These updates are typically triggered by scheduled tasks or Windows Update, resulting in the protected binary being executed from temporary or driver directories.

  • Filter/Exclusion: Exclude files with the .exe extension that are located in C:\Windows\Temp\ or C:\Windows\SoftwareDistribution\ and are executed by svchost.exe (specifically the wuauserv service) or msiexec.exe. Alternatively, whitelist specific known vendor paths if the tool is widely deployed.

• Scheduled Maintenance Jobs for Proprietary Monitoring Agents: Certain proprietary endpoint monitoring or DLP agents (e.g., older versions of Faronics, or specific banking security tokens) use ACProtect v1.3 to