What is a Man-in-the-Middle (MITM) attack and how does TLS help prevent it?

An attacker secretly relays traffic between client and server, impersonating each to the other; TLS blocks it by authenticating the server's certificate and encrypting the channel.

MITM Attack: An attacker positions themselves between client and server, pretending to be:

• The server to the client
• The client to the server

This allows them to intercept, read, and modify all communication.

TLS prevents MITM by:

• Authenticating the server via certificates
• Encrypting the communication channel

But MITM can still occur if:

• User ignores certificate warnings
• Attacker has a trusted CA certificate
• TLS is misconfigured or downgraded

Go deeper:

• Man-in-the-middle attack (Wikipedia) — the interception model, real examples, and the authentication defences that stop it.