Risk: Low
Microsoft doesn't seem to be experiencing a good start to 2006, flaw-wise. After the highly critical WMF flaw was published, exploited and patched, a feature of Windows XP and 2000, enabling PCs to automatically search for wireless connection spots, has been highlighted as a possible security flaw. If exploited, this facility could enable the victim's PC to connect unintentionally to peer-to-peer networks.
The feature was announced at a hacker's conference on Saturday 14th January and is explained on News.com: "When a PC running Windows XP or Windows 2000 boots up, it will automatically try to connect to a wireless network. If the computer can't set up a wireless connection, it will establish an ad hoc connection to a local address. This is assigned with an IP address and Windows associates this address with the SSID of the last wireless network it connected to. The machine will then broadcast this SSID, looking to connect with other computers in the immediate area.
The danger arises if an attacker listens for computers that are broadcasting in this way, and creates a network connection of their own with that same SSID. This would allow the two machines to associate together, potentially giving the attacker access to files on the victim's PC."
Some have called this a 'vulnerability' and some a 'feature' - strictly speaking, a vulnerability makes a PC do something that it's not meant to do, which is not the case in this instance. As this 'feature' is an intentional function of Windows, it can't truly be classified as a vulnerability.
Firewalls should be able to stop this happening, and those using Windows XP Service Pack 2 are not thought to be at risk. Microsoft has stated that: "Due to the design of this feature, the most appropriate method for adjusting the default behaviour is in a future Service Pack or update rollup." On Tuesday 17th January, Microsoft revealed that it was not planning to release the next Service Pack for XP until the second half of 2007, potentially meaning that this feature could remain vulnerable for up to 18 months.