Question

A development team is building a customer-facing web application hosted on cloud IaaS. The application accepts a URL from users and fetches the content of that URL to generate link previews. During a threat modeling review, a security architect warns that an attacker could abuse this feature to make the server retrieve the cloud instance metadata endpoint (e.g., 169.254.169.254) and potentially expose IAM credentials. Which mitigation most directly addresses this specific vulnerability class?

Accepted Answer

Validate and allow-list permitted destination hosts, and block requests to internal/link-local IP ranges and the metadata endpoint

Answer

Enable output encoding on all data rendered back to the browser to prevent script execution

Answer

Require multi-factor authentication for all users before they can submit URLs

Answer

Store the application's IAM credentials in a secrets manager with automatic rotation