What Is a Replay Attack?

Replay attacks are network security attacks where a malicious actor intercepts the communication between a sender and receiver. Replay attackers either delay the transmission of a message or transmit it as their own. Even with high-grade encryption, these attacks can still be successful since hackers are not required to decipher the message contained in order to be successful in their breach.

Replay attacks are utilized to trick people in a particular transaction to do what the hacker wants. By delaying the important message needed before a transaction gets finalized, they can ask the supposed receiver or sender to give them money or access to confidential information first before they decide to let the message pass through. Hackers can also intercept communication and pretend to be the actual sender to either penetrate security and authentication protocols or deceive other network participants.

These attacks are also sometimes called man-in-the-middle (MitM) attacks because they involve hackers tapping into private and encrypted communication lines. 

An effective way to prevent falling victim to such attacks is to establish more identifiers in a particular transaction. For example, apart from digital signatures attached to a message, the communicating parties could also link time codes in order to ensure the authenticity and verifiability of any exchange. Another security barrier can be to implement the requirement of one-time passwords for each transaction request in order to establish another authentication layer.