Ethical Hacking Essentials Practice Test

Which attack strategy relies on sending previously captured packets to a server to impersonate a user?

1. Man-in-the-middle attack

2. Replay attack

3. Spear phishing attack

4. Brute force attack

The correct answer is: Replay attack

The strategy involved in the correct answer focuses on the technique of taking packets that have already been transmitted over a network and sending them again to a server. This is characteristic of a replay attack, where an attacker captures and later retransmits valid data transfers to deceive the server into thinking they are the legitimate user. This method exploits the fact that the target server may not be able to distinguish between the original and the replayed packets, allowing the attacker to gain unauthorized access or perform actions impersonating the intended user. This approach is distinct from man-in-the-middle attacks, where an attacker actively intercepts and possibly alters communications between two parties, rather than using previously captured messages. Spear phishing focuses on tricking individuals into divulging their information through targeted emails rather than leveraging packet data. Meanwhile, brute force attacks involve guessing credentials by systematically trying numerous combinations, rather than capturing and resending legitimate packets to bypass authentication. Understanding how replay attacks function is crucial in the context of network security, as they highlight the importance of implementing measures such as nonce (a number used once) to ensure that each session is unique and cannot be reused by an attacker.