This rule detects the presence of the PESHiELDv0251 YARA signature, which likely identifies a specific low-severity PE file characteristic or known benign artifact that may indicate a targeted implant or staging component. Proactively hunting for this signature allows the SOC team to identify potential footholds or early-stage indicators within Azure Sentinel, ensuring that subtle or low-noise adversary activity is surfaced before it escalates into a more significant compromise.
rule PESHiELDv0251
{
meta:
author="malware-lu"
strings:
$a0 = { 5D 83 ED 06 EB 02 EA 04 8D }
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.
Windows Defender Update via MpSigUpdate.exe: The Microsoft Defender signature update process (MpSigUpdate.exe) frequently loads and executes new PE files containing updated signature databases or engine components. If the YARA rule targets specific PE headers, import tables, or section characteristics common in recent Defender builds, this legitimate background update (triggered by the Defender Update scheduled task) will match.
MpSigUpdate.exe or MsMpEng.exe, or exclude files located in C:\ProgramData\Microsoft\Windows Defender\Update\ and C:\Program Files\Windows Defender\.Visual Studio Code Extension Host (extensionHost.exe): When developers install or update VS Code extensions, the extensionHost.exe process loads numerous native Node.js addons (.node files) and compiled PE binaries for language servers (e.g., Python, C++, Rust). These binaries often have non-standard section names or import libraries that may trigger generic PE integrity checks.
code.exe or code-insiders.exe, or exclude files located under C:\Users\<User>\AppData\Local\Programs\Microsoft VS Code\ and C:\Users\<User>\AppData\Roaming\Code\.Java Runtime Environment (JRE) Native Libraries: Enterprise applications using Java (e.g., Tomcat, WebLogic, or custom internal tools) load native PE libraries like jvm.dll, jli.dll, or jawt.dll. These binaries are signed by Oracle/Java but may have section alignments or import structures that differ from standard Windows binaries, potentially matching YARA rules designed to catch packed or obfuscated PE files.