From: Cedric Blancher (blancher@cartel-securite.fr)
Date: Fri Dec 16 2005 - 16:12:32 EST
Le vendredi 16 décembre 2005 à 09:50 -0200, Demetrio Carrión a écrit :
> 1. The AP sends a 128bit number (challenge)
> 2. The client/user encrypts the challenge with the WEP key (Challenge XOR Key)
No, it's not Challenge XOR Key, it's:
Challenge XOR RC4(IV,Key)
It would be too simple if it was :
Response = Challenge XOR Key <=> Key = Response XOR Challenge
But anyway, you still have:
RC4(IV,Key) = Response XOR Challenge
And you both know Response and Challenge. So you can guess 144 bytes of
RC4(IV,Key), which allows you yoo:
1. Authenticate yourself by crafting any challenge response
using this RC4(IV,Key)
2. Inject any frame you want using this RC4(IV,Key) providing
payload does not exceed 132 bytes
You can't guess the key, however, you get sufficient knowledge to be
able to inject traffic, and then perform chopchop or aireplay attacks.
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