Owning an expensive vehicle filled with high-end features may be something many aspire to, but all that technology can mean they're more susceptible to hacks. Keyless entry and ignition systems, for example, can be easily exploited, as one man in Birmingham, England found out.

West Midlands police have released what’s thought to be the first surveillance video capturing thieves using relay boxes to steal a car. The technique works by holding one box to the wall of a house so it can pick up the signal from the owner’s key fob. Once this is received, it’s transmitted to a second box that is held close to the vehicle, which in this case was a Mercedes.

When the car detects the signal from the second box, it’s sensors are tricked into believing the key fob is present. The vehicle then unlocks and, as it also features keyless ignition, allows the criminal to start the engine and drive away. The whole process took less than one minute.

Police still haven’t identified those responsible for the theft, which took place on September 24, and the Mercedes hasn’t been recovered. The video was released recently in the hope that members of the public may be able to offer some leads.

With these types of thefts becoming increasingly popular—relay boxes can be purchased online easily—owners of keyless entry vehicles are being advised to take extra precautions. Storing the fob in a metal box such as a safe, or using a Faraday sleeve, should block the signal from being detected by the relay box. Alternatively, using an old-fashioned steering wheel lock could prevent the car being stolen, or at least slow the thieves down, and fitting the car with a tracking device is also recommended.