A major vulnerability in the Wi-Fi Protected Access II (WPA2) protocol discovered recently. These vulnerabilities include decryption, packet replay, TCP connection hijacking, HTTP content injection, and others.
Fortunately, Microsoft says that it has already issued a fix with the recently released monthly security patch. Microsoft says that anyone who applies the update or has Windows Update set to apply automatic updates should be protected.
We have released a security update to address this issue. Customers who apply the update, or have automatic updates enabled, will be protected. We continue to encourage customers to turn on automatic updates to help ensure they are protected.
A spoofing vulnerability exists in the Windows implementation of wireless networking. An attacker who successfully exploited this vulnerability could potentially replay broadcast and/or multicast traffic to hosts on a WPA or WPA 2-protected wireless network.
Multiple conditions would need to be met in order for an attacker to exploit the vulnerability – the attacker would need to be within the physical proximity of the targeted user, and the user’s computer would need to have wireless networking enabled. The attacker would then need to execute a man-in-the-middle (MitM) attack to intercept traffic between the target computer and wireless access point.
The security update addresses the vulnerability by changing how Windows verifies wireless group key handshakes.
Microsoft has posted more details here.