RDS database instance is configure to use a non-default port

Description
Confirm Amazon RDS database instances are not using default ports. This includes default ports such as MySQL/Aurora port 3306, SQL Server port 1433, and PostgreSQL port 5432.

Rationale
Using a custom port can protect against potential brute-force and dictionary attacks.

Remediation
From the console
Follow the Modifying an Amazon RDS DB instance docs to verify you’re not using a default. You can modify your port by modifying that DB instance settings.

From the command line

Run create-db-snapshot with your database instance and snapshot identifiers to create a snapshot.

create-db-snapshot.sh

    aws rds create-db-snapshot \
        --db-instance-identifier database-mysql \
        --db-snapshot-identifier snapshotidentifier

Run modify-db-instance with a new, valid port number. A list of port numbers are available.

modify-db-instance.sh

    aws rds modify-db-instance \
        --db-instance-identifier database-identifier \
        --option-group-name test-group-name \
        --db-parameter-group-name test-sqlserver-name \
        --apply-immediately