HIGH
Source
CloudSploit
ID
rds-cmk-encryption

RDS CMK Encryption

Ensures RDS instances are encrypted with KMS Customer Master Keys(CMKs).

RDS instances should be encrypted with Customer Master Keys in order to have full control over data encryption and decryption.

RDS does not currently allow modifications to encryption after the instance has been launched, so a new instance will need to be created with KMS CMK encryption enabled.