Attackers can exploit WEP weaknesses by ________.

• A. Using WEP cracking software
• B. Reading two messages encrypted with the same key
• C. Both A and B
• D. Neither A nor B

Answer: (C)

WEP flaws come from how the RC4 stream cipher is used with a short 24-bit IV. Because there are only so many IVs, frames can end up using the same keystream when the same key is involved, letting an attacker XOR two ciphertexts together to get the XOR of the two plaintexts (C1 XOR C2 = P1 XOR P2). This makes it possible to deduce relationships between the plaintexts and, with enough data (and possibly some known plaintext), recover the underlying messages or the key. Attackers also use WEP cracking software to automate this process: by collecting many frames and analyzing the IVs and ciphertexts, the software can perform statistical attacks that reveal the shared WEP key. So using cracking tools and the risk of repeated keystream from identical IVs are both valid ways to exploit WEP weaknesses, which is why both options describe real attack methods.