Control: 2.2 Ensure CloudTrail log file validation is enabled.

Description

CloudTrail log file validation creates a digitally signed digest file containing a hash of each log that CloudTrail writes to S3. These digest files can be used to determine whether a log file was changed, deleted, or unchanged after CloudTrail delivered the log. It is recommended that file validation be enabled on all CloudTrails.

Enabling log file validation will provide additional integrity checking of CloudTrail logs.

Remediation

Perform the following to enable log file validation on a given trail:

Via the management Console

1. Sign in to the AWS Management Console and open the IAM console at cloudtrail.
2. Click on Trails on the left navigation pane.
3. Click on target trail.
4. Within the S3 section click on the edit icon (pencil).
5. Click Advanced.
6. Click on the Yes radio button in section Enable log file validation.
7. Click Save.

Via CLI

aws cloudtrail update-trail --name <trail_name> --enable-log-file-validation

Note: that periodic validation of logs using these digests can be performed by running the following command:

aws cloudtrail validate-logs --trail-arn <trail_arn> --start-time <start_time> --end-time <end_time>

Default Value: Not Enabled