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Suspicious CertUtil Commands

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Suspicious CertUtil Commands

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Identifies suspicious commands being used with certutil.exe. CertUtil is a native Windows component which is part of Certificate Services. CertUtil is often abused by attackers to live off the land for stealthier command and control or data exfiltration.

Rule type: eql

Rule indices:

winlogbeat-*
logs-endpoint.events.*
logs-windows.*

Severity: medium

Risk score: 47

Runs every: 5 minutes

Searches indices from: now-9m (Date Math format, see also Additional look-back time)

Maximum alerts per execution: 100

References:

Tags:

Elastic
Host
Windows
Threat Detection
Defense Evasion

Version: 16 (version history)

Added (Elastic Stack release): 7.6.0

Last modified (Elastic Stack release): 8.4.0

Rule authors: Elastic, Austin Songer

Rule license: Elastic License v2

Investigation guide

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Rule query

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process where event.type == "start" and (process.name :
"certutil.exe" or process.pe.original_file_name == "CertUtil.exe") and
process.args : ("?decode", "?encode", "?urlcache", "?verifyctl",
"?encodehex", "?decodehex", "?exportPFX")

Threat mapping

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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/

Rule version history

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Version 16 (8.4.0 release)

Updated query, changed from:

process where event.type == "start" and (process.name :
"certutil.exe" or process.pe.original_file_name == "CertUtil.exe") and
process.args : ("?decode", "?encode", "?urlcache", "?verifyctl",
"?encodehex", "?decodehex", "?exportPFX")

Version 14 (8.3.0 release)

Formatting only

Version 12 (8.2.0 release)

Formatting only

Version 10 (8.0.0 release)

Updated query, changed from:

process where event.type == "start" and (process.name :
"certutil.exe" or process.pe.original_file_name == "CertUtil.exe") and
process.args : ("?decode", "?encode", "?urlcache", "?verifyctl",
"?encodehex", "?decodehex")

Version 9 (7.14.0 release)

Rule name changed from: Encoding or Decoding Files via CertUtil

Updated query, changed from:

process where event.type == "start" and (process.name :
"certutil.exe" or process.pe.original_file_name == "CertUtil.exe") and
process.args : ("?decode", "?encode")

Version 8 (7.13.0 release)

Updated query, changed from:

event.category:process and event.type:(start or process_started) and
process.name:certutil.exe and process.args:(-decode or -encode or
/decode or /encode)

Version 7 (7.12.0 release)

Formatting only

Version 6 (7.11.2 release)

Formatting only

Version 5 (7.10.0 release)

Formatting only

Version 4 (7.9.1 release)

Formatting only

Version 3 (7.9.0 release)

Updated query, changed from:

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

Version 2 (7.7.0 release)

Updated query, changed from:

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

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