The detection rule "AWS.S3.DeletePublicAccessBlock" is designed to monitor AWS S3 bucket configurations, particularly focusing on the public access block setting. The removal of this setting can expose sensitive data to unauthorized public access or signify preparation for data exfiltration. When the public access block is deleted, the rule triggers alerts based on CloudTrail logs capturing the API calls related to S3. The rule outlines a runbook that includes querying CloudTrail for S3 API calls made by the user, checking for changes to Bucket Policies or ACLs post-deletion, and monitoring for unauthorized access attempts to objects within the bucket from public IP addresses. The rule is classified as experimental with a medium severity level, targeting the potential risks involved in the misconfiguration of S3 bucket access controls.