AWS IAM Access Analyzer helps you identify the resources in your organization and accounts, such as Amazon S3 buckets or IAM roles, that are shared with an external entity. This lets you identify unintended access to your resources and data. Access Analyzer identifies resources that are shared with external principals by using logic-based reasoning to analyze the resource-based policies in your AWS environment. IAM Access Analyzer continuously monitors all policies for S3 bucket, IAM roles, KMS(Key Management Service) keys, AWS Lambda functions, and Amazon SQS(Simple Queue Service) queues.
Reduced visibility of externally shared resources.