At Ars Technica, you can read my long explanation of the group key weakness in WPA/WPA2 Enterprise-protected networks: The information I was given was originally under embargo, but the firm and unrelated researchers released essentially all the data except a video of an exploit in action and some of the mitigation information. Hence, the long Ars Technica piece.
Boiled down, I don't think anyone need worry about Hole196, which describes how an insider with an account on a WPA/WPA2 Enterprise network can send group broadcast packets spoofed to appear as if they originate from the access point for clients attached to that access point.
It's a hole, all right, but it requires so many particular circumstances to be met, that a spy or thief working for a company (or an outsider having gained credentialed access) would most likely have easier methods to get in--or would be detected by other means.
The best lesson I can take away from this hole? Make sure you're running virtual SSIDs if you have that option to separate guests, contractors, and others from employees; or to isolate different kinds of operations within your company.
Because each virtual SSID on an access point is treated nearly as a virtual AP, the group key isn't shared across the access point among different virtual SSID. The BSSID, or AP identifer, is unique for each virtual network on each AP.
Glenn,
So you mean inter-user privacy is not important!
Who is vulnerable when an outsider gains credential, Network or Users?
I see you giving completely two different verdicts in two successive articles of yours on "Hole196". What has been changed since you wrote https://wifinetnews.com/archives/2010/07/researchers_hints_8021x_wpa2_flaw.html.
Virtual SSIDs ! Did you mean one SSID per user ? If not then few users are anyways going to share Group Key.