This rule targets the VxHafen809 YARA signature, which identifies specific malicious or suspicious code patterns often associated with low-severity threats or early-stage infections. Proactively hunting for this signature in Azure Sentinel allows the SOC team to detect subtle anomalies or known bad artifacts that may have slipped past primary defenses, ensuring comprehensive coverage against stealthy or low-fidelity adversary activity.
rule VxHafen809
{
meta:
author="malware-lu"
strings:
$a0 = { E8 [2] 1C ?? 81 EE [2] 50 1E 06 8C C8 8E D8 06 33 C0 8E C0 26 [3] 07 3D }
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.
Scenario: A developer or DevOps engineer uses a standard build tool like MSBuild or CMake to compile a C/C++ project that includes specific header files or static libraries known to contain the byte sequences targeted by the VxHafen809 signature (often related to specific compiler artifacts or debug strings).
MSBuild.exe, CMake.exe, or dotnet.exe and the file path resides under standard development directories such as C:\dev\, C:\src\, or C:\projects\.Scenario: An IT administrator runs a PowerShell script to perform a bulk file copy or archive operation using 7-Zip (7z.exe) or WinRAR (WinRAR.exe) to compress a large folder containing mixed file types (e.g., .dll, .exe, .log) that happen to match the heuristic pattern.
7z.exe, WinRAR.exe, or tar.exe and the target file extension is not .exe or .dll, or where the working directory is a known archive staging area like C:\temp\archives\ or C:\backup\.Scenario: A security team executes a YARA scan using Yara64.exe or Yara32.exe against a large dataset of samples or a specific application directory to validate new signatures, causing the YARA engine itself to load and process files that match the rule being tested.
Yara64.exe, Yara32.exe, or yara.exe, or where the command line arguments contain the string -r (recursive