File Decoded From Base64/Hex Via Certutil.EXE
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About the rule
Rule Type
Standard
Rule Description
Detects the execution of certutil with either the "decode" or "decodehex" flags to decode base64 or hex encoded files. This can be abused by attackers to decode an encoded payload before execution
Severity
Trouble
Rule Requirement
Criteria
Action1: actionname = "Process started" AND (PROCESSNAME endswith "\certutil.exe" OR ORIGINALFILENAME = "CertUtil.exe") AND (COMMANDLINE contains "-decode ,/decode ,–decode ,—decode ,―decode " OR COMMANDLINE contains "-decodehex ,/decodehex ,–decodehex ,—decodehex ,―decodehex ") select Action1.HOSTNAME,Action1.MESSAGE,Action1.COMMANDLINE,Action1.FILE_NAME,Action1.PROCESSNAME,Action1.USERNAME,Action1.PARENTPROCESSNAME
Detection
Execution Mode
realtime
Log Sources
Windows
Author
Florian Roth (Nextron Systems), Jonhnathan Ribeiro, oscd.community
