Imagine the scene: you are driving down the high street when all of a sudden and for no apparent reason your car accelerates to a frightening speed, before slamming the brakes on.

A manufacturing fault leading to instant recall, or just the latest example of a hacker taking control of your car?

BT believes the rush to develop connected cars is putting security at risk. It says that hackers can easily gain access either via dongles or through a driver’s personal items being synced with a car’s infotainment system.

“It is not hard to hack a vehicle via the infotainment system because it goes direct into the CanBUS that links to all safety systems,” Andy Rowland, BT head of customer innovation, told delegates at a BT Fleet customer forum.

“Ultimately, hackers could disable vehicles and hold manufacturers to ransom. You could be an unwitting victim with your fleet.”

Rowland referenced ‘arbitration hijack’ whereby computers are swamped with information to bring down websites.

“You can do the same with vehicles. If you want to bring a fleet to its knees, inject a programme with zeros – it’s not difficult to do and you can do it all remotely,” he said.

“They can control headlamps, wipers, brakes and acceleration. They can also lock someone in a vehicle for ransom.”

Part of the problem is the speed with which manufacturers are developing connected cars. Rowland blames this on the pressure from Google, Apple and consumer demands which is “pushing them quicker than they want to go”.

BT is working with a number of manufacturers to prevent a hacking scenario. It is developing a software solution  which identifies elements in an IT programme that shouldn’t be there. Rowland says a viable system is “three-to-six months away”.

He adds: “One issue is that vehicles are on the road for a long time. They might be secure at the start, but hackers will eventually catch up.”

BT is confident its solution will work. It was responsible for security at the London Olympics, warding off thousands of cyber attacks every minute using a similar concept to the one it is now developing for cars.

However, fleets and company car drivers should be more aware about the range of technological devices they plug-in and sync with their cars; it can be a weak point that hackers can exploit.