Amazon S3 bucket policy modified


Detect when a S3 Bucket policy is modified.


Monitor CloudTrail and detect when S3 policies are being modified via one of the following API calls:

Triage and response

  1. Determine who the user was who made this API call.
  2. Contact the user and see if this was an API call which was made by the user.
  3. If the API call was not made by the user:
    • Rotate the user credentials and investigate what other API calls.
    • Determine what other API calls the user made which were not made by the user.


  • 18 March 2022 - Updated signal message, query and severity.
  • 16 November 2022 - Updated rule query.