Final answer:
Replay attacks involve reusing previously used hashes to authenticate and gain unauthorized access. To combat them, systems use methods like timestamps and nonce values.
Step-by-step explanation:
Replay attacks attempt to reuse previously used hashes to authenticate. This type of cybersecurity threat involves an attacker capturing a valid data transmission, such as a hash used in authentication protocols, and rebroadcasting or reusing it to gain unauthorized access to a system. To prevent replay attacks, systems often use timestamps, nonce values (numbers used once), or requiring continuous authentication at different stages of a session.
The concept is important for students studying computer security, networks or any courses related to cybersecurity. Understanding replay attacks helps to appreciate the need for secure design principles in cryptographic protocols and systems.