A developer is writing a new mobile application that employees will use to connect to an Internet- facing sensitive system. The security team is concerned with MITM attacks against the encrypted…

HSTS enforces HTTPS in browser contexts but does not add protection against MITM attacks on already-encrypted mobile application traffic or validate server identity beyond standard certificate checks.

TLS 1.3 eliminates legacy weak cipher suites, mandates forward secrecy via ECDHE, and encrypts more of the handshake to prevent passive interception and decryption. Its redesign removes known attack surfaces such as renegotiation attacks, CBC padding oracle exploits, and BEAST-class vulnerabilities. This ensures that traffic between the server and the mobile client is significantly more resistant to MITM interception and decryption attempts.

OCSP is used to verify whether a certificate has been revoked and does not prevent an attacker from intercepting or decrypting encrypted traffic in transit.

Certificate pinning ties the app to a specific certificate or public key to reject fraudulent CA-signed certificates, which is complementary but was not designated as a correct answer for this question.

Key stretching is a technique for strengthening password-derived keys through repeated hashing iterations and has no bearing on preventing MITM attacks against application traffic.