EncryptPE V22008618 WFS

Hunt Hypothesis

This rule detects the presence of the EncryptPE packer, a tool frequently used by adversaries to obfuscate malicious payloads and evade static analysis during initial access or execution phases. Proactively hunting for this signature in Azure Sentinel allows the SOC to identify potentially compromised hosts or suspicious artifacts before they can be unpacked and executed, reducing the window of opportunity for stealthy malware deployment.

YARA Rule

rule EncryptPE_V22008618_WFS: PEiD
{
    strings:
        $a = { 68 ?? ?? ?? 00 E8 52 01 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 00 00 00 00 00 00 00 00 00 00 00 00 00 6B 65 72 6E 65 6C 33 32 2E 64 6C 6C 00 47 65 74 54 65 6D 70 50 61 74 68 41 00 43 72 65 61 74 65 }
    condition:
        $a 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: A developer or DevOps engineer uses a commercial software protection tool like Themida or VMProtect to compile and package a custom internal utility or plugin before deploying it to test environments.
  • Filter/Exclusion: Exclude files located in specific development or build artifact directories (e.g., C:\Projects\Builds\, C:\Artifacts\) or exclude processes originating from known compiler/build tools (e.g., msbuild.exe, dotnet.exe, cmake.exe) when writing the encrypted binary.
• Scenario: An IT administrator deploys a new version of a legacy line-of-business application that utilizes ASPack or UPX compression/encryption for its installer or main executable to reduce file size, and the deployment script copies the file to the user’s local application data folder.
  • Filter/Exclusion: Exclude files with specific version numbers or hashes known to be part of the approved software inventory, or exclude paths under C:\Program Files\ and C:\Program Files (x86)\ for specific approved vendor directories (e.g., C:\Program Files\LegacyApp\).
• Scenario: A scheduled maintenance job runs a script that uses UPX to compress and encrypt a small configuration utility or helper script that is stored in the Temp or AppData folder for temporary execution during a system update.
  • Filter/Exclusion: Exclude files in C:\Windows\Temp\ or %LOCALAPPDATA%\Temp\ if the parent process is a known scheduled task service (e.g., Taskeng.exe) or if the file name matches a specific pattern (e.g., *.tmp, *.upx).
• Scenario: A security team or application owner uses Enigma Virtual Box to bundle a standalone .NET application or