Ensure public access is disabled for AWS Database Migration Service (DMS) instances

Allowing unrestricted, public access to cloud services could open an application up to external attack. Disallowing this access is typically considered best practice.

Public access to a DMS replication instance can be disabled by deleting the replication instance and then recreate it. Before you can delete a replication instance, you must delete all the tasks that use the replication instance. When creating the new instance ensure that the Publicly Accessible option is disabled.

In Terraform -

1. In the aws_dms_replication_instance, set the publicly_accessible field to false.

For more information, see the AWS documentation.
References:
https://docs.aws.amazon.com/dms/latest/userguide/CHAP_ReplicationInstance.PublicPrivate.html
https://registry.terraform.io/providers/hashicorp/aws/latest/docs/resources/db_instance#publicly_accessible