This YARA rule targets the Mucki Protector II malware, a known tool used for process injection and memory protection to evade detection, indicating a potential foothold for advanced persistent threats. Proactively hunting for this signature in Azure Sentinel allows the SOC to identify compromised endpoints early, leveraging the low severity as an early warning signal to investigate lateral movement or privilege escalation attempts before they mature into high-impact incidents.
rule muckisprotectorIImucki
{
meta:
author="malware-lu"
strings:
$a0 = { E8 24 00 00 00 8B 4C 24 0C C7 01 17 00 01 00 C7 81 B8 00 00 00 00 00 00 00 31 C0 89 41 14 89 41 18 80 6A 00 E8 85 C0 74 12 64 8B 3D 18 00 00 00 8B 7F 30 0F B6 47 02 85 C0 74 01 C3 C7 04 24 [4] BE [4] B9 [4] 8A 06 F6 D0 88 06 46 E2 F7 C3 }
condition:
$a0 at pe.entry_point
}This YARA rule can be deployed in the following contexts:
This rule contains 1 string patterns in its detection logic.
Antivirus/EDR Heuristic Scanning: Security tools like CrowdStrike Falcon or Microsoft Defender for Endpoint often perform in-memory scanning or heuristic analysis on executable files. This can cause the YARA rule to match against the scanner’s own working buffers or temporary copies of protected files, especially if the rule targets common string patterns found in legitimate protectors.
FalconSensor.exe, MsMpEng.exe) or filter out events where the file path resides in the security tool’s temporary directory (e.g., C:\ProgramData\McAfee\... or C:\Program Files\Microsoft Defender\...).Software Update Services: Scheduled tasks for Windows Update or third-party updaters like Adobe Creative Cloud or VMware Tools may download and execute installer packages that include integrity checkers or “protector” modules. These components often contain strings or structures that mimic the YARA signature to verify binary integrity.
svchost.exe (specifically the WaaSMplussSv service) or known updater executables (e.g., AdobeUpdateService.exe, vmware-tools.exe). Additionally, filter out events occurring during known maintenance windows or where the file path includes Updates or Installers.Development Environment Build Tasks: Developers using Visual Studio or JetBrains Rider may run post-build scripts or custom MSBuild tasks that invoke native C++/C# “protector” utilities to obfuscate or verify debug symbols. These tools are often compiled with specific string constants that trigger the YARA rule.