Ad-Hoc Wifi on laptops - beware!

[Jeff Golas]

Just had an interesting thing I never saw before. I replaced a few aging laptops with new ones, and I was cleaning up the old ones to use as loaners. For the past week or so, I've had "Public Free Wifi" showing up in my list of wireless networks, which I figured was to be expected when a new hotel just opened up directly across the street.

Anyways, I noticed it was saying 98% signal, even more than our own AP. I'm thinking MAN what kind of gear are they running over there! Thats gotta be radiating the place! This morning I saw it again and decided to double-check on it...saw it was Ad-Hoc, and immediately got suspicious. Fired up Network Stumbler and walking around, and realized the signal was strongest AT MY DESK. Came back to find it was 100% right next to the laptops I was working on. Turned out one of the laptops had several ad-hoc networks in its "preferred" network list, and was trying to connect, thus broadcasting the SSID. As soon as I deleted one, another one popped up.

After I deleted all the networks out of the preferred wireless list, it stopped broadcasting.

Moral: Disable the ability to connect to ad-hoc networks on your laptops. I know Lenovo's Access Connections has the ability to lock it down. I wasn't able to connect to the laptop, only because it had no DHCP settings. If someone wanted to - they could have connected most likely.