This rule identifies the presence of the VxEinstein YARA signature, which typically indicates the execution of a specific malware family or exploit kit component within the environment. Proactively hunting for this signature allows the SOC team to detect low-severity threats that may be used for initial access or lateral movement before they escalate into more significant compromises.
rule VxEinstein
{
meta:
author="malware-lu"
strings:
$a0 = { 00 42 CD 21 72 31 B9 6E 03 33 D2 B4 40 CD 21 72 19 3B C1 75 15 B8 00 42 }
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 security team deploys a custom YARA scanner (e.g., yara CLI or integrated into a tool like Velociraptor) that loads the VxEinstein rule into memory to scan a large directory of application binaries. The scanner process itself (e.g., python.exe or yara.exe) holds the rule definition in its heap, triggering the detection on the scanning agent rather than the target.
yara or scan and the parent process is a known security tool (e.g., velociraptor.exe, python.exe with yara in args). Alternatively, exclude if the process name is yara.exe or if the image path is under a known security tool directory (e.g., C:\Tools\Yara\).Scenario: A developer or IT admin uses a GUI-based YARA editor (such as YARA Editor or a VS Code extension for YARA) to review or edit the VxEinstein rule file. The editor process (e.g., code.exe, notepad++.exe, or yara-editor.exe) keeps the rule text in memory or a temporary file, which the YARA engine may load during a “test run” or “compile” step.
test, compile, or edit and the image path matches known editors (e.g., C:\Program Files\Microsoft VS Code\, C:\Program Files (x86)\Notepad++\). Also, exclude if the parent process is a known IDE or editor.Scenario: A scheduled PowerShell or Batch job runs a YARA scan against a network share or local disk to audit for known malware signatures.