Uncommon Network Connection Initiated By Certutil.EXE — Sigma Rule

Rule metadata and linked tags

Author: frack113, Florian Roth (Nextron Systems). Source status: test; severity: high. Source dates: 2022-09-02 / 2024-05-31.

{
  "category": "network_connection",
  "product": "windows"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: 2f3c61de042180cf7acc0f50483306fe869656a73dedfc0374f3e5f0a22df1bb

Detection logic

Original source YAML. Source-tag agreement is not proof of complete semantic coverage. This rule has not been compiled for a SIEM backend or validated against live telemetry here.

title: Uncommon Network Connection Initiated By Certutil.EXE
id: 0dba975d-a193-4ed1-a067-424df57570d1
status: test
description: |
    Detects a network connection initiated by the certutil.exe utility.
    Attackers can abuse the utility in order to download malware or additional payloads.
references:
    - https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil
author: frack113, Florian Roth (Nextron Systems)
date: 2022-09-02
modified: 2024-05-31
tags:
    - attack.command-and-control
    - attack.t1105
logsource:
    category: network_connection
    product: windows
detection:
    selection:
        Image|endswith: '\certutil.exe'
        Initiated: 'true'
        DestinationPort:
            - 80
            - 135
            - 443
            - 445
    condition: selection
falsepositives:
    - Unknown
level: high

Original YAML and metadata in JSON

False positives

• Unknown

Source references

• https://learn.microsoft.com/en-us/windows-server/administration/windows-commands/certutil