Man-in-the-middle - the James Bond method

The 'middleman attacks' (MITM) require a network in order to work. A computer interposes itself between two communication partners and functions like a 'double agent': it pretends to be the correct recipient on both sides, which is why the method is also known as a 'Janus attack', after the two-faced god of antiquity. Naturally, such attacks are very popular with industrial spies, secret services and the police.

The only way to defend against possible MITM attacks is to encrypt data consistently. Instead of meaningful information, the 'middleman' then only receives a jumble of digits that - depending on the quality of the key used - can no longer be interpreted. However, this requires mutual authentication of the communication partners, e.g. by exchanging digital certificates or keys.

In everyday life, 'Transport Layer Security' (TLS) or the Secure Shell (SSH) offer initial protection against unwanted third-party access to data traffic.