A log metric filter and alert should exist for cloud storage bucket IAM changes


It is recommended that a metric filter and alarm be established for Cloud Storage Bucket IAM changes.


Monitoring changes to cloud storage bucket permissions may reduce the time needed to detect and correct permissions on sensitive cloud storage buckets and objects inside the bucket.


Enabling of logging may result in your project being charged for the additional logs usage.


From the console

Create the prescribed log metric

  1. Go to Logging -> Log-based Metrics by visiting https://console.cloud.google.com/logs/metrics and clicking CREATE METRIC.

  2. Click the down arrow icon on the Filter Bar at the top right corner and select Convert to Advanced Filter.

  3. Clear any text and add:

    AND protoPayload.methodName="storage.setIamPermissions"
  4. Click Submit Filter. Display logs appear based on the filter text.

  5. In the Metric Editor menu on the right, fill out the name field. Set Units to 1 (default) and Type to Counter. This ensures that the log metric counts the number of log entries matching your advanced logs query.

  6. Click Create Metric.

Create the prescribed alert policy

  1. Go to https://console.cloud.google.com/logs/metrics. Under the User-defined Metrics section, identify the newly created metric.
  2. Click the kebab icon in the rightmost column for the new metric and select Create alert from Metric.
  3. Fill out the alert policy configuration and click Save. Choose the alerting threshold and configuration that makes sense for the user’s organization. For example, a threshold of zero(0) for the most recent value ensures that a notification is triggered for every owner change in the project:
   Set `Aggregator` to `Count`
   Set `Configuration`:
   - Condition: above
   - Threshold: 0
   - For: most recent value
  1. Configure the desired notifications channels in the section Notifications.
  2. Name the policy and click Save.

From the command line

  1. Create the prescribed log metric using the following command:

    gcloud logging metrics create

    See the command usage reference for more information.

  2. Create the prescribed alert policy using the following command:

    gcloud alpha monitoring policies create

    See the command usage reference for more information.


  1. https://console.cloud.google.com/logs/metrics
  2. https://cloud.google.com/monitoring/custom-metrics/
  3. https://cloud.google.com/monitoring/alerts/
  4. https://cloud.google.com/logging/docs/reference/tools/gcloud-logging
  5. https://cloud.google.com/storage/docs/overview
  6. https://cloud.google.com/storage/docs/access-control/iam-roles
  7. https://cloud.google.com/sdk/gcloud/reference/beta/logging/metrics/create
  8. https://cloud.google.com/sdk/gcloud/reference/alpha/monitoring/policies/create