Control: 2.5 Ensure that the log metric filter and alerts exist for Audit Configuration changes

Description

Google Cloud Platform (GCP) services write audit log entries to the Admin Activity and Data Access logs to help answer the questions of, "who did what, where, and when?" within GCP projects.

Cloud audit logging records information includes the identity of the API caller, the time of the API call, the source IP address of the API caller, the request parameters, and the response elements returned by GCP services.

Admin activity and data access logs produced by cloud audit logging enable security analysis, resource change tracking, and compliance auditing.

Configuring the metric filter and alerts for audit configuration changes ensures the recommended state of audit configuration is maintained so that all activities in the project are audit-able at any point in time.

Remediation

From Console

Create the prescribed log metric:

1. Go to Logging/Logs-based Metrics by visiting https://console.cloud.google.com/logs/metrics and click "CREATE METRIC".
2. Click the down arrow symbol on the Filter Bar at the rightmost corner and select Convert to Advanced Filter.
3. Clear any text and add:

protoPayload.methodName="SetIamPolicy" AND
protoPayload.serviceData.policyDelta.auditConfigDeltas:*

4. Click Submit Filter. Display logs appear based on the filter text entered by the user.
5. In the Metric Editor menu on the right, fill out the name field. Set Units to 1 (default) and Type to Counter. This will ensure that the log metric counts the number of log entries matching the user's advanced logs query.
6. Click Create Metric.

Create a prescribed Alert Policy:

1. Identify the new metric the user just created, under the section User-defined Metrics at https://console.cloud.google.com/logs/metrics.
2. Click the 3-dot icon in the rightmost column for the new metric and select Create alert from Metric. A new page opens.
3. Fill out the alert policy configuration and click Save.Choose the alerting threshold and configuration that makes sense for the organization. For example, a threshold of zero(0) for the most recent value will ensure 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

4. Configure the desired notifications channels in the section Notifications.
5. Name the policy and click Save.

From Command Line

Create a prescribed Log Metric:

• Use the command: gcloud beta logging metrics create.
• Reference for Command Usage https://cloud.google.com/sdk/gcloud/reference/beta/logging/metrics/create.

Create a prescribed Alert Policy:

• Use the command: gcloud alpha monitoring policies create.
• Reference for Command Usage https://cloud.google.com/sdk/gcloud/reference/alpha/monitoring/policies/create.