Control: 2.1.1 Ensure all S3 buckets employ encryption-at-rest

Description

Amazon S3 provides multiple encryption options to protect data at rest. With default encryption, you can set the behavior for a S3 bucket so that all new objects are encrypted when they are stored in the bucket. The objects can be encrypted using server-side encryption with either Amazon S3-managed keys (SSE-S3) or customer master keys (CMKs) stored in AWS Key Management Service (AWS KMS) (SSE-KMS).

Encrypting data at rest reduces the likelihood that it is unintentionally exposed and can nullify the impact of disclosure if the encryption remains unbroken.

Remediation

From Console

1. Open AW S3 console S3.
2. In the buckets list, choose the Name of the bucket that you want.
3. Go to Properties tab and choose Edit under Default encryption.
4. Select Enable and either select SSE-S3 or SSE-KMS.
5. Click Save changes.
6. Repeat for all the buckets in your AWS account lacking encryption.

From Command Line

Run either

aws s3api put-bucket-encryption --bucket <bucket name> --server-side-encryption-configuration '{"Rules": [{"ApplyServerSideEncryptionByDefault":{"SSEAlgorithm": "AES256"}}]}'

or

aws s3api put-bucket-encryption --bucket <bucket name> --server-side-encryption-configuration '{"Rules": [{"ApplyServerSideEncryptionByDefault": {"SSEAlgorithm": "aws:kms","KMSMasterKeyID": "aws/s3"}}]}'

Note: The KMSMasterKeyID can be set to the master key of your choosing; aws/s3 is an AWS preconfigured default.