What is a MITM attack?

• A. Intercepting and modifying communication
• B. Encrypting data in transit
• C. Brute-forcing passwords
• D. Key renegotiation

Answer: (A)

MITM, or man-in-the-middle, attack describes a situation where an attacker places themselves between two communicating parties so their messages pass through the attacker instead of directly to the intended recipient. The attacker can read the content, alter it, or inject new messages, all while both ends think they are talking to each other. This breaks confidentiality and integrity, and can also undermine trust in the communicating endpoints. For example, on a compromised Wi‑Fi network or with DNS spoofing, traffic can be diverted through the attacker who can inspect and modify what is sent.

Defenses focus on ensuring the communicating parties can verify who they’re talking to and that the messages haven’t been tampered with. Encrypting data in transit with strong, authenticated encryption and proper certificate validation (as in TLS with certificate checks) helps prevent MITM from understanding or altering content. Using trusted networks, VPNs, and integrity checks further reduces the risk.

So the core idea described is intercepting and modifying communications in transit, which is what a MITM attack does. The other options describe actions that are defensive (encrypting data to protect against MITM) or unrelated attack types (guessing passwords or a TLS protocol operation).