Security is a Shared Responsibility
It can be easy to assume Cloud Providers provide complete and total security. However, that is not the case. Amazon’s Shared Responsibility Model makes it clear that AWS is “responsible for security ‘of’ the cloud” while AWS customers are “responsible for security ‘in’ the cloud.”
Per Amazon, “Customer responsibility will be determined by the AWS Cloud services that a customer selects. This determines the amount of configuration work the customer must perform as part of their security responsibilities.”