What security weakness is presented in pre-RSNA system using 802.1X with dynamic WEP?

A.
There is support for authentication of individual users.

B.
All version of EAP used with dynamic WEP pass the user name across the wireless medium in clear text.

C.
The session key is crackable if enough traffic is transmitted using the key.

D.
With out notification, APs downgrade the security mechanism to 104-bit static WEP when the client device does not support dynamic WEP.

Explanation:
Dynamic WEP encryption keys can be generated as a by – product of the 802.1X/EAP process.These dynamic keys are generated per session per user, meaning that every time a supplicant authenticates, a new key is generated and every user has a unique and separate key. This dynamic session key is often referred to as theunicast keybecause it is the dynamically generated key that is used to encrypt and decrypt all unicast 802.11 data frames.

However, a dynamic WEP key can still be cracked and, if compromised, can indeed be used to decrypt data frames. The current WEP cracking tools such as Aircrack-ng can obtain a WEP key in a matter of minutes. Therefore, dynamic WEP still has severe data privacy risks.