Car Theft by Relay Attack: How to Stop It

There's a gadget some car thieves in Melbourne use that lets them steal a keyless car without the key, without breaking a window, without even touching the car, in about a minute. It costs around twenty dollars, and it's sold openly online.

It's called a relay attack, and it's worth understanding, because most people have no idea their car is vulnerable until it's gone.

How it works

Your keyless entry car only starts because it thinks the key is nearby. The key broadcasts a signal, the car reads it, and it unlocks and starts. The relay attack is simple. One thief stands at your front door holding a small antenna up against the house. If your keys are on the hall table or hanging by the door, that antenna picks up the signal and relays it to the second thief standing at the car. The car sees the relayed signal, assumes the key is right there, and opens. And starts.

All in the time it takes you to put down your groceries.

This has been happening overseas for years, and reports of it are climbing in Sydney and Melbourne as more keyless cars hit the road. Even the manufacturers quietly acknowledge it. That's why many newer cars only let the key talk to the car if the key actually moves, they've disabled the "constant signal" that made the old relay trick so easy. But if your car is a few years old, you can't just assume it's got that protection.

The cheap fix

The good news is this is one of the cheapest car-security problems to solve. A Faraday pouch is a small lined bag that blocks the signal completely. Drop your keys in it and the car can't hear them, so the antenna at your door picks up nothing. They cost a few dollars at an automotive shop or online.

The even cheaper fix is habit. Don't leave the keys by the front door or on that dish near the window. Put them somewhere central in the house, or at the back. If the signal can't reach a wall, it can't be relayed.

You can also check whether your car actually turned its constant signal off. Read the owner's manual, or search your make and model along with "relay attack protection". If it's not there, treat the keys as if they're always transmitting.

Where locksmiths fit in

Relay attacks are about the electrics, not the physical lock, so a lot of people don't think to talk to a locksmith about them. But we work on car keys every single day. If you're not sure whether your car's keyless system is safe, or you'd like a spare key cut and programmed so you've always got a way in, that's very much our lane.

It's a small thing, but it's the difference between a thief walking off with your car and walking off empty-handed.