Google Cloud Storage Bucket enumerated

Goal

Detect when a service account lists out GCS Buckets.

Strategy

This rule lets you monitor GCS bucket admin activity audit logs to determine when a service account invokes the following method:

  • storage.buckets.list

Triage and response

Determine whether this service account should be making list bucket calls.

  • If the account was compromised, secure the account and investigate how it was compromised and if the account made other unauthorized calls.
  • If the owner of the service account intended to make the ListBuckets API call, consider whether this API call is needed. It could cause a security issue for the application to know the name of the bucket it needs to access. If it’s not needed, modify this rule’s filter to stop generating signals for this specific service account.