Google Cloud Firewall Modified or Deleted — Sigma Rule

Rule metadata and linked tags

Author: Austin Songer @austinsonger. Source status: test; severity: medium. Source dates: 2021-08-13 / 2022-10-09.

{
  "product": "gcp",
  "service": "gcp.audit"
}

Pinned original Sigma rule · Detection Rule License 1.1

Source SHA-256: a885d49d11447f2414e4b372ed0dc22fb6289a527e5568fb472a603f4beec83f

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: Google Cloud Firewall Modified or Deleted
id: fe513c69-734c-4d4a-8548-ac5f609be82b
status: test
description: Detects  when a firewall rule is modified or deleted in Google Cloud Platform (GCP).
references:
    - https://cloud.google.com/kubernetes-engine/docs/how-to/audit-logging
    - https://developers.google.com/resources/api-libraries/documentation/compute/v1/java/latest/com/google/api/services/compute/Compute.Firewalls.html
author: Austin Songer @austinsonger
date: 2021-08-13
modified: 2022-10-09
tags:
    - attack.defense-impairment
    - attack.t1685
logsource:
    product: gcp
    service: gcp.audit
detection:
    selection:
        gcp.audit.method_name:
            - v*.Compute.Firewalls.Delete
            - v*.Compute.Firewalls.Patch
            - v*.Compute.Firewalls.Update
            - v*.Compute.Firewalls.Insert
    condition: selection
falsepositives:
    - Firewall rules being modified or deleted may be performed by a system administrator. Verify that the firewall configuration change was expected.
    - Exceptions can be added to this rule to filter expected behavior.
level: medium

Original YAML and metadata in JSON

False positives

• Firewall rules being modified or deleted may be performed by a system administrator. Verify that the firewall configuration change was expected.
• Exceptions can be added to this rule to filter expected behavior.

Source references

• https://cloud.google.com/kubernetes-engine/docs/how-to/audit-logging
• https://developers.google.com/resources/api-libraries/documentation/compute/v1/java/latest/com/google/api/services/compute/Compute.Firewalls.html