GCP Audit: Storage Bucket Modified or Deleted via Storage API

title: "GCP Audit: Storage Bucket Modified or Deleted via Storage API"
id: 2aa3e5a0-73ec-47b8-a75d-275d72ba21e0
status: test
description: This rule identifies Google Cloud Storage bucket changes by matching Cloud Audit log method names for bucket delete, insert, update, and patch. Attackers can use these operations to disrupt availability or change where data is stored by creating or modifying buckets. It relies on GCP audit telemetry that records storage API method_name events associated with the change.
references:
  - https://cloud.google.com/storage/docs/json_api/v1/buckets
  - https://github.com/SigmaHQ/sigma/blob/master/rules/cloud/gcp/audit/gcp_bucket_modified_or_deleted.yml
author: Austin Songer @austinsonger, Huntrule Team
date: 2021-08-14
modified: 2022-10-09
tags:
  - attack.impact
logsource:
  product: gcp
  service: gcp.audit
detection:
  selection:
    gcp.audit.method_name:
      - storage.buckets.delete
      - storage.buckets.insert
      - storage.buckets.update
      - storage.buckets.patch
  condition: selection
falsepositives:
  - Storage Buckets being modified or deleted may be performed by a system administrator. Verify whether the user identity, user agent, and/or hostname should be making changes in your environment.
  - Storage Buckets modified or deleted from unfamiliar users should be investigated. If known behavior is causing false positives, it can be exempted from the rule.
level: medium
license: DRL-1.1
related:
  - id: 4d9f2ee2-c903-48ab-b9c1-8c0f474913d0
    type: derived