Tuesday, November 6, 2007

WiFi Jamming and Defense

The most popular WiFi standards today, 802.11b and 802.11g, both operate in the 2.4 GHz (Giga Hertz) frequency band and are susceptible to interference from other products operating in the 2.4 GHz band including microwave ovens, Bluetooth devices, baby monitors and cordless telephones. 802.11n, currently in Draft 2.0 standard (with projected standard approval in the fall of 2008), can use both 2.4 GHz and 5 GHz frequencies.

WiFi signal jamming can be intentional using jamming or unintentional using devices that use the same frequency band. For example, if you live in an apartment or condominium with neighbors close by you could be unintentionally jamming their WiFi network every time you use your 2.4 GHz wireless phone.

Dedicated WiFi Jammers are extremely easy to find on the Internet and also relatively easy for someone with electronics and soldering experience to make. One of the more popular home-made jammers is called the Wave Bubble, a self-tuning, wide-bandwidth portable RF (Radio Frequency) jammer that is small enough to fit inside a pack of cigarettes. The Wave Bubble (also refered to as Wavebubble) is tunable and can be used to jam two-band systems such as cell and single-band systems like cordless phones, GPS, WiFi and Bluetooth devices.

Wave Bubble jamming frequency tuning is done by plugging the device into the USB port on a computer and entering the frequencies that are to be blocked. The user can even enter more than one frequency range and the device will advance to the next frequency in memory each time it is powered off and on. Wave Bubble output power is relatively low at .1 Watt for the high frequency bands and .3 Watts for the low frequency bands. Even at these low power levels, with a properly tuned external antenna, the effective range is about a 20 foot radius. With just the internal antenna range is significantly less.

Some of you are probably asking why I'm writing about this stuff - in my opinion it is no secret (try Googling "wireless jammers")....... and....... I have always believed that in any situation, in order to properly defend against an attack, it is important to understand as much as possible about the method of attack.

Now - regarding defense - the Daily Cup of Tech has a good list of tips to help defend against someone jamming your WiFi network. Here it is:

  1. Always wire your access points. This way, you cannot be jammed from the server.
  2. Wire access points directly back to the central switch and try to avoid bridging your connections. This will help prevent a cascade effect.
  3. Do periodic audits of your “air space”.
  4. Don’t broadcast that you are using wireless technology. Turn off your SSID on your wireless systems.
  5. Do not place server rooms on an external wall. This could allow someone to jam your wireless link without even entering your office.
  6. Catalog and label all server room hardware. Periodically audit your hardware lists.
  7. Tightly restrict physical access to your server rooms.
  8. Train all employees to immediately questions unaccompanied strangers in the office.
Once again - remember - these devices are illegal in the United States.

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