Friday, 22 June 2007

Home WiFi Jamming

To conclude a trilogy of WiFi Security blogs this week, I’m going to touch on an accidental home encounter I had with WiFi signal jamming. As we become ever more WiFi enabled, particularly in the UK, where there has been a bit of WiFi explosion of late, with whole areas of cities becoming WiFi enabled. There is little doubt in my mind that we will become more and more dependant on WiFi networks. Anyone who has read any formal IT Security book will know about the CIA Triad, Confidentially, Integrity and Availability, well security wise this post is going to be about Availability, i.e. jamming the WiFi signal. Now you might think WiFi jamming sounds a bit far fetched and that it would require a lot of expensive equipment and expertise, but as I accidently discovered recently, it does not have to be.

A couple of weeks ago I finally gave in and bought my kids a Nintendo Wii, well I figure it keeps them physically active while playing the video games, which sounds like a fair trade off to me. Anyway I placed the Wii under the main household TV and then tried to connect the Wii up to my home WiFi network, which would allow the Wii to receive software updates, weather forecasts and even browse the web through the Wii’s Opera web browser, however I soon discovered the Wii wouldn’t connect to the WiFi network.

So after an or so hour of troubleshooting, by temporary stripping down all my WiFi security, and then actually plugging the WiFi Router in downstairs as close as possible to the Wii’s location, I discovered the Wii could only pick up my WiFi network signal from a maximum distance of 10 centimetres! Even then the bandwidth (network speeds) appeared to be far too slow. Well I gave up with it for the day as the kids wanted to play Wii Sports. I just thought I had a dodgy WiFi card built into my Wii, but later that night I had an epiphany while watching Satellite TV upstairs in bed.

You see I have Satellite TV, which feeds into the main TV, however earlier this year I wanted the ability to watch all those lovely Satellite TV channels on the bedroom TV as well, so I bought a cheap "Technika" TV broadcasting solution from the local supermarket for £20 ($40), instead of paying over odds with the Satellite TV company for a second set top Sat Box. The equipment consisted of a broadcast unit which attached to the SCART OUT of the downstairs Satellite TV box, which sends TV pictures, Sound and even the remote control infra red signals to a receiver, which connects to a SCART IN on the bedroom TV. My epiphany was the theory that TV broadcast unit was somehow jamming the WiFi signal, especially considering the Wii and TV broadcast unit both resided under the main TV. So I switched off the TV broadcast unit and immediately the Wii connected to the internet.

The following day I did some experiments with my laptop, I noted with the TV broadcast unit switched on, in parts of the house it dropped the WiFi network signal strength by two thirds, while downstairs it wiped all connectivity to the WiFi network.

So it is possible to have effective WiFi jamming at a very cheap cost, I imagine with some customisation you could increase the range of the WiFi jamming and make it a mobile device.

I can think of numerous bad uses for WiFi jamming, especially using it as a decoy while performing other attacks, but perhaps one good use could be to enforce a no-WiFi policy, although you’d probably need to check the broadcasting laws first.

13 comments:

ibneko said...

Very interesting. While I'd have more of a use for a cellphone jammer that I could carry around (arrrgh, loud people on public transportation and people driving while talking on cellphones when it's illegal...), a wifi jammer could have some uses as well... although I can't think of any reasons beyond pranking that would make me want to use that sort of technology right now. (In the future thou, if I get a job and need to kill off rogue wifi spots... this may be the perfect cheap solution. Although I'm not sure how we'd purchase them over here in the states.)

Have you tried changing the channel that the wifi network is running on though?

Dave Whitelegg CISSP said...

No I've not tried changing the channels, but I do plan to carry out further experients, I'll def. try changing the channels.

Павел said...

It gain my attention. I'll try various channels, too. And post my results later...
Besides,...
World famous company Agnitum Ltd., specializing in security, gives some recommendations about using WiFi: WiFi Security Basics

Guest said...

A legitimate use - I could use this for my classes. Students in the back row often surf the net when they are supposed to be learning the subject at hand. Would be nice to disable wifi within the classroom for the duration of the lesson.

Anonymous said...

Good site, liking all the info on here.
Thanks.

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Satellite TV: CardSharing

WiFi Jamming said...

Mini Portable Cellphone Jammer Blocking Wifi J-260D

WIFI Jammer said...

Cool post as for me. I’d like to read something more concerning this topic.

WIFI JAMMER said...

Thanks for your post, now more and more eu people know what is a wifi jammer and why they need a wifi jammer, u do a good job i think!

WiFi Jammer said...

WiFi is rather unreliable signal you know. For example two wifi routers that operate in the same area can cause loss of any wifi signals at all because they will be "jamming" one another. That's why modern wifi routers have built-in autoadjustment of the frequencies so if some frequency is already in use, router starts to use a slightly different frequency.

WIFI JAMMER said...

WIFI jammers, oh no, our boss use this to block our phone wifi. But also thanks for this great helpful post about it!

jammer said...

WiFi jamming is not that big of a problem, just enable password security.

Infinate_Horizon said...

I'd like a portable mobile phone jammer to carry with me at work, tired of the lazy teens who do nothing and force me to work harder while they sit and text message in the back...

signal jammer said...

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