Managing Keys in an Open System

It is very difficult to manage encryption keys that never change. Whenever
you leave the same key on your wireless station or access point for
any extended period of time, it becomes highly vulnerable to being
hacked. It is important to use a unique method of managing your keys
or at least storing them in databases that are not necessarily connected
to your network.

Authentication Concerns

In the 802.11b environment, it is important to note that there is no perpacket
authentication mechanism. This means that you cannot analyze
the packet level to determine if any given packet of data transmitted
across your WLAN is being corrupted by someone trying to destroy the
validity of your data or cause interference on your network.

You are still vulnerable to disassociation attacks with 802.11 associate/
disassociate messages that are unencrypted and unauthenticated.
This could allow forged disassociation messages to be used against
clients. Your best defense under these circumstances is to add a keyed
message integrity check (MIC).

In an open system authentication there are no levels to protect your network.
This means that someone could easily log into your network without
a user identification or authentication. Furthermore, there is no central
point of authentication, authorization, or support for accounting types.
Even though you might believe that having an encryption cipher in
RC4 will protect you, it is important to know that it will not offer you
protection against plain text types of hacker attacks.
We have discussed WEP keys, but many systems are vulnerable to
having their keys reverse engineered just because user passwords are
known. This can effectively negate any type of WEP protection you have
on your network and leave you quite vulnerable to an attack in which a
hacker eavesdrops on your network connection and determines ways to
decipher the mission-critical data on your WLAN as well as on your
wired LAN.
Another problem is that there is no support for any method of extended
authentication that includes:


Public/private-key certificates

Smart cards

One-time passwords

Biometric authentication devices

Token cards

There is no method of managing dynamic unicast session key (as
opposed to a multicast global authentication key) for each wireless
workstation. Such issues involving key management and the rekey of
global keys are a known weakness in many WLAN implementations.