AHTeamEPProtector03fakeASPack212FEUERRADER

Hunt Hypothesis

This rule detects the presence of a specific YARA signature associated with the AHTeamEPProtector tool, which adversaries may use to pack or obfuscate executable files to evade static analysis and signature-based detection. Proactively hunting for this indicator allows the SOC to identify potentially compromised endpoints where attackers are employing lightweight packing techniques to hide malicious payloads within the Azure environment.

YARA Rule

rule AHTeamEPProtector03fakeASPack212FEUERRADER
{
      meta:
		author="malware-lu"
strings:
		$a0 = { 90 [46] 90 FF E0 60 E8 03 00 00 00 E9 EB 04 5D 45 55 C3 E8 01 00 00 00 EB 5D BB ED FF FF FF 03 DD 81 EB }

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 .NET Framework Compilation Tasks: Developers or build engineers using older versions of Visual Studio or MSBuild to compile C# projects that embed specific resource strings or metadata matching the 212FEUERRADER signature. This often occurs in CI/CD pipelines running on Windows agents where intermediate PDB or DLL files are scanned before deployment.

  • Filter/Exclusion: Exclude files located in standard build output directories (e.g., C:\Program Files\Microsoft Visual Studio\*\*\bin\, C:\BuildAgent\_work\) or files with extensions .pdb, .dll, and .exe created within the last 15 minutes by processes named MSBuild.exe or VBCSCompiler.exe.

• Third-Party Application Update Mechanisms: Enterprise applications like Adobe Creative Suite, JetBrains IDEs (IntelliJ, WebStorm), or SAP GUI that download and execute temporary update packages or installer stubs. These installers often use packed or obfuscated binaries that may coincidentally match the YARA pattern if the packing algorithm is similar to the one targeted by the rule.

  • Filter/Exclusion: Exclude processes spawned by known update services such as AdobeUpdateService.exe, JetBrainsUpdater.exe, or SAPUpdate.exe. Additionally, exclude files in temporary update folders like C:\ProgramData\Adobe\Update\ or %LOCALAPPDATA%\JetBrains\.

• Antivirus/Endpoint Protection Self-Update: Security tools like CrowdStrike Falcon, Carbon Black, or SentinelOne perform self-updates by downloading new rule packs or engine components. These updates may be stored in temporary locations or executed via helper scripts that contain binary signatures matching the detection logic, especially if the update package is compressed or encrypted in a way that mimics the fake AS pack.

  • Filter/Exclusion: Exclude processes with names like `F