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MediumSplunk security contentMichael Haag +1

CertUtil With Decode Argument

The following analytic detects the use of CertUtil.exe with the 'decode' argument, which may indicate an attempt to decode a previously encoded file, potentially containing malicious payloads. This detection…

Description

The following analytic detects the use of CertUtil.exe with the 'decode' argument, which may indicate an attempt to decode a previously encoded file, potentially containing malicious payloads. This detection leverages data from Endpoint Detection and Response (EDR) agents, focusing on command-line executions involving CertUtil.exe. This activity is significant because attackers often use CertUtil to decode malicious files downloaded from the internet, which are then executed to compromise the system. If confirmed malicious, this activity could lead to unauthorized code execution, further system compromise, and potential data exfiltration.

Detection logic

Detection requirements

Platform
ESXiLinuxmacOSWindows

The rule states no platform. This is derived from the ATT&CK technique it maps to.

Log source category
crowdstrike_processrollup2sysmon_eventid_1windows_event_log_security_4688

Known benign triggers

  • Typically seen used to `encode` files, but it is possible to see legitimate use of `decode`. Filter based on parent-child relationship, file paths, endpoint or user.

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