Relay Attack Car Theft: How Thieves Unlock Keyless Cars

Relay Attack Car Theft: How Thieves Unlock Keyless Cars

It's 2:14 on a Tuesday morning. Your keys are in the bowl by the front door, thirty feet from your car, behind a wall and a deadbolt. A stranger is standing at the edge of your driveway holding a gadget about the size of a paperback. A second stranger is standing next to your car. Nobody has touched a lock, broken a window, or hacked anything. Your car just opens.

That's a relay attack, and it's the least dramatic way a car has ever been stolen. It's also why I'm writing about a car theft on a scam blog: it's a con run on a machine instead of a person. The thieves lie to your car, and your car believes them.

How a relay attack actually works

Your keyless car is constantly listening for its fob. When the fob is close enough, the car says "okay, that's the owner" and unlocks. The trick is that "close enough" is decided by radio signal, and radio signals can be picked up, boosted, and handed off.

Here's the sequence, as Help Net Security describes it:

1. Thief one stands near your house with a device that picks up and boosts your fob's signal. It works even if the fob is just sitting on a table inside.
2. Thief two stands next to your car with a second device that receives the boosted signal.
3. The car accepts it as the real key. It unlocks, and then the thieves can start it.

Because the car thinks the owner did all of this, the factory alarm typically stays silent, according to the same article. No broken glass either. A local TV segment from WRDW in Georgia makes the same point: relay theft can leave "no broken glass or obvious damage," and the owner finds an empty parking spot and nothing to show for it.

This isn't a hypothetical nobody's tried. In June 2026, two men were sentenced in the UK to 49 and 58 months after admitting a conspiracy to steal 25 cars, mostly BMWs and Mercedes, using relay equipment between October and December 2025, according to a report on the case. That's a UK case, and a lot of the best-documented relay theft is European, but the equipment doesn't care what country your driveway is in.

Why this is harder to spot than a normal scam

With a phishing text, there's a moment where you could have noticed something off. With a relay attack there's no moment. You didn't click anything, you didn't answer a call, you didn't do anything wrong. The first sign is the empty driveway.

It also doesn't take a genius to do it. One security-gear maker quoted in the Help Net Security piece says what surprises them most is how easy it is to buy equipment that can copy keys or relay signals. That tracks with what I keep seeing: the scary part of modern fraud is rarely the technology, it's how cheap and ordinary it has become.

And your car's maker may not be saving you. Help Net Security reports that Germany's ADAC auto club tested more than 800 keyless vehicles and found only about 15% were adequately protected against relay attacks. That's one club's test set, not every car on the road, but it's a good reason not to assume yours is in the lucky 15%.

The red flags (there aren't many, which is the point)

You can't spot this one in the moment, so the "red flags" are really risk factors worth knowing:

• You have passive keyless entry. Doors unlock as you approach with the fob in your pocket, and you start the car with a button.
• Your fobs live near the front door. WRDW's segment calls out fobs kept near front doors, garage doors, and exterior walls as the easiest to reach, and notes that spare fobs on the same system are exposed too.
• The fob is in a bowl, on a hook, or on a windowsill. That's the shortest possible distance for a thief's gadget.
• Your spare fob sits in a drawer near the car. Same system, same signal, forgotten by everyone, including you.
• You assume the car locks itself. Some don't, and plenty of owners assume they do.

What actually closes the hole

The fix for a relay attack is boring on purpose: if the fob can't broadcast, there's nothing to relay. Two objects do that.

A Faraday pouch for each fob. It's a signal-blocking sleeve. You drop the fob in, and the radio goes quiet. A Faraday key fob pouch is built for exactly this, and WRDW puts the going price of this kind of pouch at about $15.

A signal-blocking box at the door. If the whole household's fobs, spares included, live in one shielded place, you're not relying on everyone remembering a pouch at 11pm. The TICONN Faraday box is the "everything goes in here when you walk in" version. In our house, nothing gets past the front door at night except Blue and Belle, and the same rule should apply to car fobs.

Both are also in the Cautellus Shop, alongside the rest of the short list of boring gear I'd actually recommend.

Here's the part people skip: test the pouch. WRDW's advice is simple and I'd follow it exactly. Put the fob inside, close it, walk up to the car, and try the door. If the car still recognizes the key, the pouch isn't working. Tracker, a UK vehicle-recovery company, has warned that imitation pouches are flooding the market and that some offer little more than peace of mind. A ten-second test beats finding out the hard way.

A few free upgrades also help:

• Keep fobs farther inside the house, away from doors, windows, and exterior walls.
• Check your owner's manual or ask a dealer whether your fob can turn its wireless signal off or go to sleep.
• Lock the car manually and check that it actually locked.

What a Faraday pouch doesn't do

I'd rather lose a sale than oversell this, so here's the honest part.

A pouch "only protects against relay attacks," as WRDW puts it, and it "does not prevent every type of modern vehicle theft." Help Net Security describes other routes, including plugging a programming tool into the car's OBD-II port to write a new key, and cloning a key by copying the fob-and-car exchange. A shielded fob doesn't touch either. A steering wheel lock is a useful deterrent but won't stop an electronic unlock.

It also doesn't protect you from the scam version of this story. Cars bring out a whole category of fake texts: a made-up "your registration expired" notice, an unpaid-toll message, a "vehicle fine" with a payment link. A pouch does nothing about those, and the DMV fine text is a good example of how that one reads. Those texts all live on the text message scams hub. If one lands on your phone, paste it into the scam text checker before you tap anything. You get one free trial scan every 30 days, no card needed.

And a pouch won't help with the other boring-object attacks: a washed check from your mailbox, a rigged public USB port, or a tap-to-pay skimmer in a crowd. Different attack, different object. That's the whole philosophy behind my gear picks: one cheap thing for one specific hole.

If your car was already stolen

Calm, in order:

1. Call the police and file a report. Say the car has keyless entry and that there was no sign of forced entry. That detail matters.
2. Call your insurer. Same detail. Ask what documentation they need.
3. Check for a tracker. If you had a GPS or Bluetooth tracker hidden in the car, give police the location. Help Net Security lists this as a layered defense for exactly this reason.
4. Secure the other fobs. Any spare fob on the same system should go in a shielded pouch or box now.
5. Think about what was inside. If the car held a garage door opener or paperwork with your address on it, change the garage code and keep an eye out for mail you don't recognize.

Nobody who loses a car this way did anything dumb. The thieves are the ones standing in a stranger's driveway at 2am with a gadget.

How not to become the next victim

• Put every fob, spare included, in a tested Faraday pouch or box at home.
• Keep that box away from exterior walls and windows.
• Test any new pouch with the walk-up-to-the-door check.
• Lock manually and confirm it locked.
• Add a visible deterrent like a steering wheel lock.
• Ask your dealer whether your fob has a sleep or off mode.
• Hide a tracker in the car if you can.

Tonight, before bed, take the fobs out of the bowl and put them in the box by the door. That's the whole fix, and it takes about ten seconds.

Sources: Help Net Security, "Thieves can pull off keyless car theft in under a minute" (June 2026); WRDW, "What the Tech: How thieves quietly unlock cars without keys" (Sept. 10, 2026); Hits Radio, relay-theft sentencing report (June 24, 2026); Fleet World / Tracker Network UK, imitation Faraday pouches.