The AWS S3 Access Error rule is designed to monitor and detect access errors occurring during object retrievals from Amazon S3 buckets. Access errors can arise due to several factors such as insufficient access permissions, the non-existence of requested buckets, or other underlying system issues. The rule aggregates logs with an HTTP status of 403 or 500 for S3 operations and triggers when the specific error conditions are met, marking it as an 'Info' severity alert. It also includes heuristic checking for specific error codes like `AccessDenied` and `SignatureDoesNotMatch`. This rule necessitates additional investigation via a runbook that guides response actions based on the cause of the detected error, helping discerning whether it is a transient issue or something that needs further remediation. Organizations can consult AWS's documentation on S3 error codes for further references.