Ensure that your AWS S3 buckets are not publicly accessible via bucket policies in order to protect against unauthorized access. Allowing unrestricted access through bucket policies gives everyone the ability to list the objects within the bucket (ListBucket), download objects (GetObject), upload/delete objects (PutObject, DeleteObject), view objects permissions (GetBucketAcl), edit objects permissions (PutBucketAcl) and more. Cloud Conformity strongly recommends using bucket policies to limit the access to a particular AWS account (friendly account) instead of providing public access to everyone on the Internet.
This rule can help you with the following compliance standards:
- Payment Card Industry Data Security Standard (PCI DSS)
- General Data Protection Regulation (GDPR)
- APRA
- MAS
- NIST 800-53 (Rev. 4)
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 access to your S3 buckets via bucket policies can allow malicious users to view, get, upload, modify and delete S3 objects, actions that can lead to data loss and unexpected charges on your AWS bill.
Audit
To determine if your Amazon S3 buckets allow unauthorized public access via bucket policies, perform the following:
Remediation / Resolution
To restrict access to your publicly accessible S3 buckets via bucket policies, perform the following:
References
- AWS Documentation
- Amazon Simple Storage Service (S3) FAQs
- Managing Access Permissions to Your Amazon S3 Resources
- Using Bucket Policies and User Policies
- Access Policy Language Overview
- Bucket Policy Examples
- Editing Bucket Permissions
- AWS Command Line Interface (CLI) Documentation
- s3api
- list-buckets
- get-bucket-policy
- delete-bucket-policy
- put-bucket-policy
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You are auditing:
S3 Bucket Public Access Via Policy
Risk level: Very High