During an engagement, a penetration tester needs to break the key for the Wi-Fi network that uses WPA2 encryption. Which of the following attacks…

The Key Reinstallation Attack (KRACK) is a protocol-level vulnerability that targets the WPA2 4-way handshake, the process used to establish a new session key. An attacker can trick a victim into reinstalling an already-in-use key by manipulating and replaying these handshake messages. This forces the reuse of cryptographic nonces (numbers used once) with the same key, which breaks the stream cipher's security properties (e.g., AES-CCMP). Consequently, an attacker can decrypt packets, hijack TCP connections, and inject malicious content into the traffic stream, effectively breaking the WPA2 encryption for that session.

A. ChopChop: This is an attack primarily used against the older and insecure WEP protocol to decrypt packets; it is not effective against WPA2's robust cryptographic design.

B. Replay: A generic replay attack involves re-transmitting valid data but does not, by itself, break the WPA2 encryption key or allow for traffic decryption.

C. Initialization vector: IV attacks exploit weaknesses in how IVs are generated and reused, a critical flaw in WEP that was specifically addressed and mitigated in the WPA2 protocol.

1. Vanhoef

M.

& Piessens

F. (2017). Key Reinstallation Attacks: Forcing Nonce Reuse in WPA2. Proceedings of the 2017 ACM SIGSAC Conference on Computer and Communications Security

1313–1328. In Section 3

"The 4-Way Handshake

" the paper details how retransmissions of Message 3 can lead to the reinstallation of the pairwise encryption key (PTK)

and Section 4 explains how this leads to nonce reuse and packet decryption. https://doi.org/10.1145/3133956.3134028

2. National Institute of Standards and Technology (NIST). (2017). NVD - CVE-2017-13077. National Vulnerability Database. The description states

"An attacker can force the reuse of a nonce... in a way that allows for key reinstallation." This is one of the primary CVEs assigned to the KRACK vulnerability

confirming it as an official

documented attack against WPA2.

3. Stallings

W. (2017). Cryptography and Network Security: Principles and Practice (7th ed.). Pearson. In Chapter 20

"Wireless Network Security

" the text contrasts the vulnerabilities of WEP

such as IV collision attacks

with the more robust mechanisms of WPA2

which were later found to be vulnerable to attacks like KRACK. This academic textbook places the attacks in their correct protocol context.