Auditing AWS S3 Bucket Permissions

When to Use

• When conducting a security assessment of AWS environments to identify publicly exposed data
• When onboarding a new AWS account and establishing a security baseline for storage resources
• When responding to an alert about potential S3 data exposure from AWS Trusted Advisor or Security Hub
• When compliance frameworks (SOC 2, PCI DSS, HIPAA) require periodic review of data access controls
• When a breach or credential compromise necessitates immediate review of all accessible S3 resources

Do not use for auditing non-AWS object storage (use provider-specific tools), for real-time monitoring (use S3 Event Notifications with Lambda), or for auditing S3 access patterns (use S3 Access Analyzer or CloudTrail S3 data events).

Prerequisites

• AWS CLI v2 configured with credentials that have s3:GetBucketPolicy, s3:GetBucketAcl, s3:GetBucketPublicAccessBlock, s3:GetEncryptionConfiguration, and s3:ListAllMyBuckets permissions
• Prowler installed (pip install prowler) for automated CIS benchmark checks
• S3audit or similar enumeration tool for quick public bucket detection
• Access to AWS Organizations if auditing across multiple accounts
• Python 3.8+ with boto3 for custom audit scripts