replay attack - Computer Definition
Using a previously recorded or captured message to attack a computer system or network or to gain access to somewhere one is not authorized to be (a form of identity theft). Many people consider biometrics to be a very secure means of authentication and a rather effective means of fighting off a replay attack. However, the 1983 movie War Games showed how someone can fool cryptographic systems if the systems are created in a naÃ¯ve and vulnerable manner. For example, a cracker can record an authorized person’s voice and replay it in order to access a system. This replay attack can be enhanced if the cracker uses digitalized information. The 1997 movie Gattaca showed how even more sophisticated DNA-based computer security systems could be fooled. The movie tells a futuristic story about a genetically imperfect man who has an unrequitable need to travel in space, so he takes on the identity of an athlete who is genetically able to pursue the dream.
Barmala, C. Attack. [Online, 2004.] Christian Barmala’s Free CA Website. http://ca.barmala.com/attack.en.php#replay; Rees, C. Plot Summary for Gattaca (1997). [Online, May 19, 2005.] Internet Movie Database, Inc. Website. http://www.imdb.com/title/ tt0119177/plotsummary.
A breach of security in which information is stored without authorization and then retransmitted to trick the receiver into unauthorized operations such as false identification or authentication or a duplicate transaction. For example, messages from an authorized user who is logging into a network may be captured by an attacker and resent (replayed) the next day. Even though the messages may be encrypted, and the attacker may not know what the actual keys and passwords are, the retransmission of valid logon messages is sufficient to gain access to the network. Also known as a "man-in-the-middle attack," a replay attack can be prevented using strong digital signatures that include time stamps and inclusion of unique information from the previous transaction such as the value of a constantly incremented sequence number. See piggybacking and hijacking.