Available at https://console.aws.amazon.com/trustedadvisor/, Trusted Advisor is a tool that makes several recommendations around the topic of security, as well as cost optimization, performance, and fault tolerance.

Specifically, on the topic of security, you will be able to validate your security groups, your IAM usage, and make sure that MFA is enabled on the root account:

If you have a support plan, this tool will offer a few more insights into the resources mentioned earlier and on other AWS services including Route 53, RDS, S3, CloudFront, and ELB.

The tool is free and easy to use but doesn't provide as much information as our next tool, AWS Inspector.