Ensure that your Amazon S3 buckets are not configured to allow anonymous users to modify access control permissions in order to protect your S3 data against unauthorized access. An Amazon S3 bucket that grants public WRITE_ACP (EDIT) access, can allow everyone on the Internet to edit the bucket permissions and gain full access to your S3 bucket.
This rule can help you with the following compliance standards:
This rule can help you work with the AWS Well-Architected Framework
This rule resolution is part of the Cloud Conformity Security & Compliance tool for AWS
Granting public WRITE_ACP access to your Amazon S3 buckets can allow anonymous users to edit bucket permissions in order to view, upload, modify, and delete S3 objects within your buckets. Allowing this type of access is dangerous and can lead to data breach, data loss, or economic Denial-of-Service (EDoS) attacks (i.e. uploading a large number of files to drive up the costs of cloud computing). To meet security and compliance requirements, avoid granting WRITE_ACP (EDIT) permissions to the "Everyone (public access)" grantee in production.
To determine if your Amazon S3 buckets are configured to allow public WRITE_ACP access, perform the following operations:
Remediation / Resolution
To restrict public WRITE_ACP access to your Amazon S3 buckets using Access Control Lists (ACLs) perform the following operations:Note: An S3 bucket can be deemed compliant if implements either
"AccessControl": "Private"or sets the
"PublicAccessBlockConfiguration"feature options to
true. The following CloudFormation template uses both for added security.
- AWS Documentation
- Amazon S3 FAQs
- Access Control List (ACL) Overview
- Managing ACLs in the AWS Management Console
- Configuring ACLs
- CloudFormation Documentation
- Terraform Documentation
- AWS Provider
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You are auditing:
S3 Bucket Public 'WRITE_ACP' Access
Risk level: Very High