A company deploys a distributed web application on Amazon EC2 instances behind an Application Load Balancer (ALB) that terminates TLS. The company requires that TLS traffic to the ALB remain secure even if the certificate’s private key is compromised. How should a security engineer satisfy this requirement?

The correct answer is to create an HTTPS listener that uses a security policy enforcing cipher suites with Perfect Forward Secrecy (PFS). PFS ensures that even if a server's private key is compromised in the future, past recorded TLS sessions cannot be decrypted. This is because a unique session key is generated for each session, and this key is not derivable from the long-term private key. Using a certificate managed by ACM is good practice for certificate management but doesn't inherently protect against private key compromise for past sessions. Enabling Server Order Preference helps prioritize strong ciphers but doesn't guarantee PFS if the client doesn't support them or if the policy allows non-PFS ciphers. A TCP listener does not terminate TLS, so it cannot enforce TLS security policies or PFS at the ALB level.