Black Hat Last year, the Black Hat presentation by Charlie Miller and Chris Valasek caused Chrysler to recall 1.4 million vehicles to install a software update after they proved they could remotely hack Jeeps.

This year, in Las Vegas, the pair showed us how to defeat that update.

The dynamic duo praised Chrysler's efforts to secure their vehicles, noting that the new firmware won't accept commands via the builtin diagnostic port if the car is traveling more than five miles per hour. Vehicles also can't receive data via their wireless Sprint connection unless they are fully patched against the vulnerabilities Miller and Valasek found, which makes remote hacking difficult to virtually impossible.

So instead, the two focussed on direct physical attacks against the car's Controller Area Network (CAN) bus, by plugging into the OBD-II (on-board diagnostics) port fitted as standard to modern vehicles to control the onboard computers. Using the official mechanics software program, costing $1,650, they went for a rummage in the car's operating system.

Using this method the two found that, with nine hours work, they could brute force their way into the car's sensitive subsystems, including the speedometer. By manipulating this so that the car thought it was going under the 5MPH limit, they found it was possible, although not easy, to take control of the vehicle's steering and brakes via diagnostic messages.

They found that the adaptive cruise control was pretty secure because it automatically shut down if someone tried to push it commands. By reverse-engineering the system, the two managed to get control of the brakes and throttle, though.

They also successfully got into the steering system and were able to make the wheel very difficult to turn, and to turn it 90 degrees – with the latter move piling their test vehicle into a ditch. This could be done at speed and has the potential to kill an unsuspecting driver.

The emergency brake was also vulnerable. The pair were able to permanently lock the brake on and said it would be non-trivial to fix. Miller suggested that a mechanic would probably have to replace the entire braking system, as that would be easier than trying to fix it.

Chrysler appears relaxed about this year's hacking, since it requires physical access to the car to work – you basically have to break in and fit a gizmo to the diagnostics port to disrupt the vehicle's operations, rather than hack it anonymously from the other side of the internet.

On the other hand, you could sneak the device into the OBD-II with some wireless comms and take over the car while it's being driven.

All these issues could be stopped if only car manufacturers built a basic intrusion detection system into their cars, such as the Can-no hackalator 3000 that the two built in 2014. When asked by The Register why this wasn't being done, Miller said he didn't know, but as cars are typically designed over five-year cycles, the automakers may be working on one and just haven't rolled it out yet. In the meantime, he isn't worried about mass car hacking.

"It's hard, so I'm not worried about it," he said. "It's not like one day someone is going to make all the cars in the world stop. But we can't ignore it just because I'm not worried about it."

This will be the last time Miller and Valasek demonstrate their car hacking skills. Valasek said they had been doing this for four years now and it was time to pass the baton to other researchers. In the meantime, the two are concentrating on their day jobs: developing automated car software for Uber. ®