An attacker uses a network sniffer to capture the packets of a transaction that adds $20 to a gift card. The attacker then user a function of the sniffer to push those packets back onto the network again, adding another $20 to the gift card. This can be done many times. Which of the following describes this type of attack?

A. Integer overflow attack
B. Smurf attack
C. Replay attack
D. Buffer overflow attack
E. Cross-site scripting attack

Answer: C. Replay attack