AWS Certified Solutions Architect – Associate (SAA-C03) — Question 486

A company runs an infrastructure monitoring service. The company is building a new feature that will enable the service to monitor data in customer AWS accounts. The new feature will call AWS APIs in customer accounts to describe Amazon EC2 instances and read Amazon CloudWatch metrics.

What should the company do to obtain access to customer accounts in the MOST secure way?

Answer options

• A. Ensure that the customers create an IAM role in their account with read-only EC2 and CloudWatch permissions and a trust policy to the company’s account.
• B. Create a serverless API that implements a token vending machine to provide temporary AWS credentials for a role with read-only EC2 and CloudWatch permissions.
• C. Ensure that the customers create an IAM user in their account with read-only EC2 and CloudWatch permissions. Encrypt and store customer access and secret keys in a secrets management system.
• D. Ensure that the customers create an Amazon Cognito user in their account to use an IAM role with read-only EC2 and CloudWatch permissions. Encrypt and store the Amazon Cognito user and password in a secrets management system.

Correct answer: A

Explanation

The most secure way to manage cross-account access in AWS is by leveraging IAM roles with a trust policy, which eliminates the need to share or manage long-term credentials. Storing IAM user access keys or Amazon Cognito credentials in a secrets manager, as suggested in other options, introduces unnecessary security risk and administrative overhead. A trust policy allows the monitoring service to securely assume the role using AWS STS temporary security credentials.