SigmaHQ/rules/windows/process_creation/win_susp_certutil_command.yml

title: Suspicious Certutil Command
id: e011a729-98a6-4139-b5c4-bf6f6dd8239a
status: experimental
description: Detects a suspicious Microsoft certutil execution with sub commands like 'decode' sub command, which is sometimes used to decode malicious code with
    the built-in certutil utility
author: Florian Roth, juju4, keepwatch
date: 2019/01/16
modified: 2020/11/28
references:
    - https://twitter.com/JohnLaTwC/status/835149808817991680
    - https://twitter.com/subTee/status/888102593838362624
    - https://twitter.com/subTee/status/888071631528235010
    - https://blogs.technet.microsoft.com/pki/2006/11/30/basic-crl-checking-with-certutil/
    - https://www.trustedsec.com/2017/07/new-tool-release-nps_payload/
    - https://twitter.com/egre55/status/1087685529016193025
    - https://lolbas-project.github.io/lolbas/Binaries/Certutil/
logsource:
    category: process_creation
    product: windows
detection:
    suffixes_1:
        CommandLine|contains:
            - ' -'
            - ' /'
    selection:
        CommandLine|contains:
            - 'decode '
            - 'decodehex '
            - 'urlcache '
            - 'verifyctl '
            - 'encode '
    suffixes_2:
        CommandLine|contains:
            - '-'
            - '/'
    certutil:
        Image|endswith: '\certutil.exe'
        CommandLine|contains:
            - 'URL'
            - 'ping'
    condition: suffixes_1 and selection or 
               suffixes_2 and certutil
fields:
    - CommandLine
    - ParentCommandLine
tags:
    - attack.defense_evasion
    - attack.t1140
    - attack.command_and_control
    - attack.t1105
    - attack.s0160
    - attack.g0007
    - attack.g0010
    - attack.g0045
    - attack.g0049
    - attack.g0075
    - attack.g0096        
falsepositives:
    - False positives depend on scripts and administrative tools used in the monitored environment
level: high