“Free Public WiFi” Isn’t WiFi, It’s Just A Free Nuisance

If you’re like me you’ve seen “Free Public WiFi” show up on your mobile device, laptop, etc. when looking for wifi connectivity in the wild. Ever wonder why it never works? It doesn’t work because it doesn’t really provide wifi of any kind. In fact it’s not even a wifi hotspot. It’s an “ad hoc” network on an uncountable number of machines.

“Free Public WiFi” must have been the name of a free wifi network at some point but an old (and since patched) Windows XP flaw has caused many computers to identify themselves as “Free Public WiFi”. When an XP machine can’t connect to a hotspot it’s been configured for it will start looking for other hotspots and try to connect with them. This will lead it to attempt to connnect to nearby “ad hoc” networks. “Ad hoc” networks are peer-to-peer networks that are good for tasks such as copying files from one computer to another. But if the host of the “ad hoc” network isn’t actually configured to allow access the XP machine trying to connect to it will create it’s own “ad hoc” network with the same name as the one it couldn’t connect with. The same flaw has caused many other “ad hoc” networks to spread using the name of the network they originated on.

If you’ve been ‘infected’ by “Free Public WiFi” you’re not in any immediate danger. But “Free Public WiFi” may be an attack vector for a hacker.

What can you do to avoid this issue? Update your XP machine to SP3 (this only affects earlier versions). Also don’t try to connect to “Free Public WiFi” or any “ad hoc” networks you don’t know about. As for other devices? There’s probably no issue with infection/hacking vector but I’d avoid connecting to “Free Public WiFi” or any “ad hoc” networks you don’t know about just the same. You can never be too safe.

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