Go to any new car dealer and sit down in one of the vehicles on the showroom floor, and you'll likely notice the absence of one feature that was once universal on all cars: an ignition key hole. While some new cars still retain key holes on the steering column and driver's door in case of battery failure, most new cars these days rely on keyless entry and ignition. It's undeniably convenient to have your car unlock automatically as you walk up, and to start at the push of a button, all while the key fob is still in your pocket.

An example of an RFID-blocking key fob guard from Silent-Pocket.com

However, this entry and ignition system poses a potentially serious security threat due to the growing risk of keyless car theft. Car manufacturers have made it difficult for criminals to start from scratch and spoof a specific vehicle's key signal out of thin air. But it is possible to bounce the real key's signal over long distances, and tech-savvy thieves are doing just that.

By getting within the signal radius of your car key — usually a few yards — a criminal can use a range-extender or repeater device to amplify that signal to ten times that range. Say your car is sitting in your driveway while you're asleep, and your keys are inside the house behind your locked front door. Thieves can stand outside the house, pick up the signal, and bounce it in real time to make your car think the key is right next to it. The car unlocks, and they hop in, press the start button, and drive off.

One criminal stands near the house with the repeater device, while the other opens the door.

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In case this sounds hard to believe, here's a video of this exact scenario happening to a new Mercedes sedan in England last week. It took the masked perpetrators just 20 seconds to enter the car, and about a minute to make a clean getaway.

You might be thinking the car will shut off once it realizes the key isn't inside, but that's not normally the case. For safety reasons, most cars will sound a chime and give a warning about the key, but will remain running until they're turned off. This is so the owner won't crash or end up stranded if the key fob battery dies while driving. Unfortunately, it also allows car thieves to sneak off to a chop shop or even flee the country.

This video from ADAC, a German automotive organization, explains how these attacks work and demonstrates another scenario:

So, what can you do to prevent keyless car theft? Until vehicle manufacturers establish a standard way to prevent these attacks, the best solution is to block your key's signal when it's not in use. This can be accomplished by placing your key in a faraday cage or thick-walled metal box at home, ideally away from the exterior walls of your house. You can also carry your keys in an RFID-blocking sleeve or pouch — this limits convenience slightly but can prevent attacks like the restaurant example in the video above.

While this form of car theft is still somewhat rare, it's worth considering that your shiny new car and its fancy security system can be easily defeated if a determined criminal tricks it into thinking you've handed him the key fob.

Written by Patrick McCarthy