What is the MOST secure way for a security engineer to implement this functionality?
Configure read-only access to the object by using a bucket ACL. Remove the access after a set time has elapsed.
Implement an IAM policy to give the user read access to the S3 bucket.
Create an S3 presigned URL. Provide the S3 presigned URL to the user through the application.
Create an Amazon CloudFront signed URL. Provide the CloudFront signed URL to the user through the application.
Explanations:
Configuring read-only access using a bucket ACL does not ensure secure, temporary access to specific users. ACLs are less flexible and can expose data to unintended users. Removing access after a set time is not automated and can lead to security risks if not handled correctly.
Implementing an IAM policy to grant read access to the S3 bucket is overly broad, as it may grant unnecessary permissions to users who should only access specific objects. IAM policies apply at the bucket level rather than on individual objects, which can lead to potential exposure of sensitive data.
While creating an S3 presigned URL allows temporary access to an object, it is not the most secure method for a custom domain name scenario. Presigned URLs are tied to the S3 bucket and may expose the S3 endpoint directly, which could lead to potential security vulnerabilities.
Creating an Amazon CloudFront signed URL provides a secure way to deliver content. It enables custom domain names, offers access control, and integrates caching and performance optimizations. This method ensures that access to the S3 objects is tightly controlled and can be restricted based on expiration times, IP addresses, and other criteria, making it the most secure option.
If memory serves me right, the answer is:
Create an Amazon CloudFront signed URL. Provide the CloudFront signed URL to the user through the application.