A hacker has altered a user's 3-Way Handshake in order to gain access to their...

A stateful firewall would intelligently deny traffic from a hacker attempting to alter a user's 3-Way Handshake to gain access to their session. Stateful firewalls keep track of the state of active connections and can recognize if an incoming packet is part of an established session. This allows them to detect and block unauthorized access attempts that do not match the known state of a connection.