A security researcher warned over the weekend that the way Windows XP and 2000 look for wireless connections can be used by hackers to dip into unsuspecting users' hard drives.
Calling the flaw a "configuration error" rather than a true vulnerability, researcher Mark Loveless claimed that when Windows powers up but doesn't find a wireless access point, it creates an ad hoc network, complete with the SSID, the Wi-Fi network identifier, like "linkysys" or "actiontec," of the last network connection.
Other laptops, when set to sniff for the same SSID, can listen for such connections, and when they find one, create a peer-to-peer link between the two PCs, said Loveless. Once connected, the attacker could conceivably introduce malicious code and/or access files on the laptop's hard drive.
"In Windows 2000 and Windows XP and [XP] SP1, this all happens in the background without the user's knowledge," Loveless said in his notes on the bug. "On Windows XP SP2, the user is notified it has 'attached' to an ad-hoc network, when in fact it has simply started advertising the ad-hoc network."
Loveless also claimed that in real-world tests, he would have been able to connect to 11 different laptops on four airline flights.
Microsoft, said Loveless, was notified of the problem in mid-October, and since has not only confirmed the issue, but said it would address it in the next Service Pack. That's not saying much, however, since Windows 2000 will have no new Service Packs, while the next for Windows XP, SP3, won't release until late 2007.
In the meantime, he recommended that users disable wireless when it's not used, or set Windows' wireless to connect only to access points, not individual notebooks.
To do the latter, click on the wireless icon in the System tray, and open the Wireless Network Connection Properties window. Click on the Wireless Network tab, click on the Advanced button, and click on "Access point (infrastructure) networks only."
An even easier way to block the "feature," said security experts Tuesday, is to use any firewall, even Windows XP's default firewall.