You're stuck in an airport and don't feel like paying $9.95 for Internet access ... but wait! You stumble upon a network called "Free Public WiFi." The heavens are smiling, right? Wrong. Available in thousands of locations across America, "Free Public WiFi" is an "ad hoc" network that connects you to another computer in the vicinity instead of the Internet, wireless security expert Joshua Wright tells NPR. The "zombie network" appears to have spread via a bug in old versions of Windows XP—and it provides an easy access point for hackers.
As NPR explains, when computers running the older version of XP can't find one of its "favorite" wireless networks, it creates an "ad hoc" one named after the last network joined ... and the "Free Public WiFi" name then becomes available to nearby computers, enticing their unsuspecting owners to join, explains Wright. He compares its spread to how "a zombie takes a hold of one person, bites them, and they become infected by this zombie virus." He believes it may originally have been created by somebody trying to trick a friend into connecting "so he would get a Web page with some kind of a gross image or childish prank." Other "zombie" networks to steer clear of include "linksys," "hpsetup," "tmobile," and "default."