Man-in-the-middle attacks

A man-in-the-middle attack is a cyberattack where an attacker intercepts and possibly alters communications between two parties who believe they are directly communicating with each other. The attacker can insert themselves between the two parties and relay messages to make them think they are talking privately, when in reality the attacker controls the entire conversation. To succeed, the attacker must impersonate each endpoint well enough to satisfy their expectations, but most cryptographic protocols have authentication measures in place to prevent these attacks.