4.3.1. Amazon S3 Security (Bucket Policies, ACLs, Public Access Block)
First Principle: Amazon S3 security fundamentally protects data by providing granular access controls (Bucket Policies, ACLs), encryption, and preventative measures (Public Access Block) to prevent unauthorized access and data leaks.
Amazon S3 (Simple Storage Service) is a highly durable and scalable object storage service, often used for sensitive data. Securing S3 buckets and their objects is paramount to prevent data breaches.
Key Amazon S3 Security Controls:
- Bucket Policies: Resource-based IAM policies attached directly to an S3 bucket.
- Purpose: Control access to the bucket and its objects. Define who (principals) can perform what actions (e.g.,
s3:GetObject,s3:PutObject) on which resources (e.g., specific objects or prefixes). - Use Cases: Granting cross-account access, enforcing public read-only access for static websites.
- Purpose: Control access to the bucket and its objects. Define who (principals) can perform what actions (e.g.,
- Access Control Lists (ACLs): A legacy access control mechanism for S3 buckets and objects.
- Purpose: Grant read/write permissions to specific AWS accounts or predefined groups.
- Note: Bucket policies are generally preferred for most use cases due to their greater granularity and flexibility.
- S3 Block Public Access: A set of settings that allow you to block public access to S3 buckets and objects at the account level or for individual buckets.
- Purpose: A critical preventative security feature to prevent accidental public exposure of S3 buckets. Recommended to enable at the account level.
- Encryption at Rest: Encrypts data in S3 using SSE-S3, SSE-KMS, or SSE-C.
- Versioning: Protects against accidental overwrites and deletions by keeping multiple versions of an object.
- S3 Object Lock: Provides Write Once Read Many (WORM) capability for compliance.
Scenario: You need to secure a new Amazon S3 bucket that will store highly sensitive customer data. This data must never be publicly accessible, and only specific IAM roles should be able to read and write to it. All data must also be encrypted.
Reflection Question: How do Amazon S3 security features (Bucket Policies, ACLs, Public Access Block, encryption) fundamentally protect data by providing granular access controls and preventative measures to prevent unauthorized access and data leaks from your S3 buckets?