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How do you prevent car relay theft?

What is car relay theft?

Car relay theft, relay attack or keyless car theft is when a criminal tricks your vehicle’s keyless entry system into thinking that the wireless remote is in range. It only works on cars where you can enter and start the car without using a key – in other words, many new cars. The increased popularity of this method of accessing and starting a car is because it removes the bulky barrel lock in the steering column which can cause damage to the driver’s knees in a crash. It’s also more convenient and (supposedly) more secure because you can’t just jam a screwdriver into the ignition barrel.

How do you do a relay attack?

You only need three things to execute this attack:

  1. Your wireless car key within transmitting distance of the car
  2. A person near the key with a device that tricks the key into sending a response, i.e. broadcasting its signal
  3. A person near the car with a receiver that dupes the car into thinking it is the key

Bear in mind that some remote car keys will work 80-100m away, so putting the keys in your house doesn’t mean your car is immune to this type of attack. In fact, you could also be sitting in a nearby cafe and the attack could be executed.

How do you prevent relay attacks from happening?

The easiest way is to stop your key from being accessible using a wireless transmission. This is fairly easy: put it in your microwave, a metal tin, a Faraday sleeve or wallet, or your fridge. These prevent the attack vector. Don’t leave your key in the hallway overnight because wireless signals pass through doors, walls and windows.

Providing a secondary form of security is a good idea, too. Wheel locks will work if you have to park on the road, or you could park behind locked gates or in a garage to help thwart thieves.

There are systems which use a secondary immobiliser, e.g. a switch that only you know the location of, but given enough time, a thief will find it.

If you are still worried about theft, install a GPS tracking device.

Who is at risk of relay attacks?

These types of attacks do require a level of sophistication above just breaking a window. You are not at risk if your car requires you to put a key in the ignition and turn it. If your car only requires you to push a start button, you are at risk. Thieves are more likely to target expensive cars as the rewards are higher. You are less likely to be targeted if you have obvious countermeasures (physical locks, separate tracking alarm, etc).

Darren has owned several companies in the automotive, advertising and education industries. He has run driving theory educational websites since 2010.

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