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Certutil De-Obfuscate_Decode Files

Anvilogic Forge

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Summary
This detection rule monitors the use of 'certutil', a command-line utility that can be exploited by threat actors to decode or deobfuscate files, particularly Portable Executable (PE) files. The primary use of certutil in this context is related to malware operations, specifically those executed by notable threat actors like FIN13, Kimsuky, and Revil, among others. The rule focuses on identifying the use of certutil with the '-decode' or '-decodehex' parameters, which are indicative of the decoding process used to extract potentially malicious payloads from encoded formats. The detection logic leverages Windows Sysmon event data to track event IDs that signal user activity involving certutil, filtering for specific terms that indicate decoding actions. By harnessing fields such as event time, host, user, and associated process details, this rule aims to highlight suspicious activities potentially linked to malware operations or unauthorized data exfiltration practices. It is a crucial part of monitoring Windows environments for signs of code obfuscation techniques commonly used by adversaries.
Categories
  • Windows
  • Endpoint
Data Sources
  • Process
  • Windows Registry
  • Application Log
ATT&CK Techniques
  • T1140
Created: 2024-02-09