AWS CloudTrail Logs Encrypted Using KMS CMK

Risk	Remediation Effort
High	Medium

This policy validates that AWS CloudTrails Logs are encrypted at rest with customer managed KMS CMKs.

CloudTrail logs include API level log events within your AWS account. It is a best security practice to encrypt these logs to reduce the chance they are exposed to unauthorized viewers to gain insight into your AWS environment.

Remediation

To remediate this, enable CloudTrail encryption using a KMS CMK.

Using the AWS Console
1. Access the trails tab of the AWS CloudTrail Console.
2. Select the CloudTrail where you wish to enable encryption at rest.
3. Under the "Storage location" header, select the edit :pencil2: button.
4. Select the "Encrypt log files with SSE-KMS" radio button.
5. Select an existing key with an appropriate an appropriate KMS key policy to allow CloudTrail to encrypt the bucket, or select the "Create a new KMS key" radio button.
6. If you selected "Create a new KMS key", name the key.
7. Select the "Save" button

Using the AWS CLI
1. Run the following command to attach the KMS key you intend to use for encryption to the CloudTrail trail:
aws cloudtrail update-trail --name <trail_name> --kms-key-id <kms_key_id>
2. Be sure the KMS key policy grants CloudTrail permissions to describe KMS keys, encrypt with KMS keys, and decrypt with KMS keys.

References

• CIS AWS Benchmark 2.7 "Ensure CloudTrail logs are encrypted at rest using KMS CMKs"

• Encrypting CloudTrail Log Files with AWS KMS–Managed Keys (SSE-KMS)