Ensure that your Amazon RDS production databases are not using 'awsuser' as master username, regardless of the RDS database engine type used, instead a unique alphanumeric string must be defined as the login ID for the master user.
Since 'awsuser' is the Amazon's example (default) for the RDS database master username, many AWS customers will use this username for their RDS databases in production, therefore malicious users can use this information to their advantage and frequently try to use 'awsuser' for the master username during brute-force attacks.
To determine if your existing RDS database instances are using "awsuser" as master username, perform the following:
To change the master username for your RDS database instances you need to re-create them and migrate the existing data to the new instances. To set secure master usernames for all your RDS databases, perform the following steps: