ASProtectv11

Hunt Hypothesis

This hypothesis targets the presence of executables packed with ASProtect v11, a technique frequently employed by adversaries to obfuscate malware payloads and evade static analysis. Proactively hunting for these files in Azure Sentinel allows the SOC team to identify suspicious binaries that may be hiding malicious logic, thereby reducing the risk of undetected compromise through common packing mechanisms.

YARA Rule

rule ASProtectv11
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 60 E9 ?? 04 [2] E9 [7] EE }

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 Deployment: Organizations often deploy older, unpatched line-of-business applications or drivers that were compiled and packed with ASProtect v11 to protect intellectual property or reduce file size. These legitimate binaries may reside in C:\Program Files\ or C:\Windows\System32\drivers\ and trigger the rule during routine patching or software installation.
  • Filter/Exclusion: Exclude files located in standard application directories (C:\Program Files\, C:\Program Files (x86)\) that have a valid digital signature from a known vendor (e.g., Microsoft, Oracle, SAP) and were modified within the last 30 days.
• Driver and Firmware Updates: Hardware vendors (such as Intel, AMD, or specific peripheral manufacturers) may ship driver packages or firmware update utilities packed with ASProtect v11 to compress the payload. These files are typically executed by setup.exe or install.exe from temporary folders or vendor-specific directories during scheduled maintenance windows.
  • Filter/Exclusion: Exclude files in C:\Windows\Temp\ or vendor-specific temp directories (e.g., C:\Intel\, C:\AMD\) that are child processes of known installer executables (e.g., msiexec.exe, setup.exe) and have a valid digital signature.
• Third-Party Antivirus/Security Tools: Some security products or endpoint detection tools may use ASProtect v11 to pack their own update modules or rule sets to prevent tampering. These files are often stored in the vendor’s installation directory and are accessed by the security service process.
  • Filter/Exclusion: Exclude files located in the installation directory of known security vendors (e.g., C:\Program Files\Kaspersky\, C:\Program Files\Symantec\) that are owned by a trusted