If you use your PC to access the Internet in public places, you've probably seen the "Free Public WiFi" network and tried connecting to it. You may have also noticed, with frustration, that this network does not connect you to the Internet. That's because it's a "zombie network," an issue caused by an out-of-date Windows XP bug. NPR explains the glitch:
When a computer running an older version of XP can't find any of its "favorite" wireless networks, it will automatically create an ad hoc network with the same name as the last one it connected to -- in this case, "Free Public WiFi." Other computers within range of that new ad hoc network can see it, luring other users to connect.
If you connect to an "ad hoc network," you're merely connecting to another PC in your area. Wireless security expert Joshua Wright describes the viral spread of this "network" in terms of a zombie bite. "[A] zombie takes a hold of one person, bites them and they become infected by this zombie virus," Wright told NPR. This issue is nothing new, however: back in 2006, Houston Chronicle writer Dwight Silverman began noticing the "Free Public WiFi" network in airports and even in the Chronicle's conference room. He attributed the network to a glitch in Windows XP and Windows 2000. "Generally," Silverman wrote, "you want to avoid ad hoc networks in public places. At best, they're a radio signal to nowhere; at worst, they could be someone looking for a vulnerable PC to compromise." In 2008, Microsoft released the Windows XP Service Pack 3 as a fix for the bug. While Microsoft has also eliminated the bug from more recent versions of Windows, as not everyone performs regular updates, the issue persists.
"Free Public WiFi" isn't the only network you should watch out for: NPR notes that you should also be wary of networks like “linksys,” "hpsetup," "tmobile" or "default," although The Next Web points out that these are sometimes legitimate, albeit unsecured, networks.