My Amazon Simple Storage Service (Amazon S3) bucket's access control list (ACL) has an AWS account listed that I don't recognize. The account is listed in a format similar to the following:
How can I find out which account this is?
When you view your bucket's ACL in the Amazon S3 console, any accounts listed under Access for other AWS accounts are accounts that don't own your bucket. These accounts are added to the ACL by the AWS account root user or an AWS Identity and Access Management (IAM) user who has permissions to edit the ACL for that bucket.
The unique identifier listed for accounts in an Amazon S3 bucket's ACL is a user's canonical user ID. To be able to map a canonical user ID back to the account, you must have access to the account. For instructions on how to find an account's canonical user ID, see Finding Your Account Canonical User ID.