Encoding or Decoding Files via CertUtil

IMPORTANT: This documentation is no longer updated. Refer to Elastic's version policy and the latest documentation.

Encoding or Decoding Files via CertUtil

Identifies the use of certutil.exe to encode or decode data. CertUtil is a native Windows component which is part of Certificate Services. CertUtil is often abused by attackers to encode or decode base64 data for stealthier command and control or exfiltration.

Rule indices:

winlogbeat-*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-6m (Date Math format, see also Additional look-back time)

Maximum signals per execution: 100

Tags:

Elastic
Windows

Rule version: 1

Added (Elastic Stack release): 7.6.0

Rule query

edit

event.action:"Process Create (rule: ProcessCreate)" and
process.name:"certutil.exe" and process.args:("-encode" or
"/encode" or "-decode" or "/decode")

Threat mapping

edit

Framework: MITRE ATT&CK^TM

Tactic:
- Name: Defense Evasion
- ID: TA0005
- Reference URL: https://attack.mitre.org/tactics/TA0005/
Technique:
- Name: Deobfuscate/Decode Files or Information
- ID: T1140
- Reference URL: https://attack.mitre.org/techniques/T1140/

« Disable Windows Firewall Rules via Netsh Execution via Signed Binary »