During the early hours of the morning there was an attempt to enter and presumably steal various vehicles on my street, detected well after the fact via householders reviewing CCTV motion detection alerts. There is only ever one person in each of the video clips, he obviously has a device in the palm of one hand and was moving around between properties on opposite sides of the road too quickly to be working in tandem with an unseen second operative with a device to boost a return signal.

Is it feasible to perform an amplification relay attack without a device to boost a return signal from the fob, or was something else going on here? I am 99% confident that the one vehicle he managed to open was locked.

This got me thinking about how best to reduce their window of safety re detection and reporting the crime, would it be feasible to detect the initial amplified car to fob signal within the property and use this as a trigger event to home automation, alarm or similar? Obviously this relies upon whatever they are doing being a form of relay attack and not something new / different.

Whatever they were doing, they knew enough not to bother with Teslas.

1 Answer 1


With keyless entry there are several concerns related to proximity -- are the keyfob and car close enough together for error-free communication, and is the car security system happy with the measured signal strength from the keyfob.

The attacker is obviously not interested in discarding keyfob signals simply because they're weak. So it's possible to perform the relay entirely from next to the car, or from any point between the car and keyfob.

One thing manufacturers can do to guard against this is to not rely on signal strength alone, but also timing. A response coming through a relay/repeater will necessarily be slower than one from a nearby keyfob.

  • Thank you, so on this basis it does at least seem reasonable to assume a detector inside the property for the initial car to fob challenge could work as an alert event generator. Existing OEM investment and installations aside it would make sense to migrate to technologies supporting time of flight measurement to avoid the man in the middle attacks. Mar 31, 2023 at 6:41

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