Hi,
WEP is considered by many as a fundamentally broken security device since it contains inherent weaknesses. For this reason the best advice from the security community is to opt for a stronger means of securing wireless networks e.g. WPA2.

It's important to keep unauthorised hosts off your network. Once an unwanted visitor is inside your network they can work on attacking your machines. There are techniques such as ARP poisoning that may be used for man-in-the-middle attacks, bypassing the protection offered by SSL/TLS or the intruder might simply attack your computers/routers directly.

Make every effort to keep strangers off your wireless network as you would a wired network. There are many aspects to security that are as or more important than encrypting your network traffic.

Jim

It really depends on the strength of the encryption. Cracking WEP only connects you to that network.  In my experience the average cracker doesn’t know what to do with intercepted encrypted traffic and looks for easier targets because they are out there.   If all the hosts are extremely well fortified and the communication is using strong encryption, most crackers are going to be dead in the water and there will be little they can do directly against that particular network other than take the entire network down.  The reality is, you won’t find well fortified boxes behind something like WEP, because if you have an Admin that conscientious in the first place, WEP would be the last thing used. 

Kev - thanks for your input - I have done session hijack in lab on my ceh course but not on ssl -
i have a ssl vpn deployed and am unsure if i should be concerned about users accesing it from public wifi spots that i have no control over

i am now not sure wether wireless makes any difference to the ssl encryption.

although i suppose if can compromise the wireless n/w then session hijack is easier than doing it for a users coming over dial up - as that would have to be done blind as you can't get the packets back - source based routing won't work.
which leaves me coming back to - is it even possible