Arthur C. Clarke said that “Any sufficiently advanced technology is indistinguishable from magic”. He was a sci-fi writer, though, and not a security guy. Maybe it should read “Any sufficiently advanced tech has security flaws”. Because this is the story of breaking into a car through its headlight.
In a marvelous writeup, half-story, half CAN-bus masterclass, [Ken Tindell] details how car thieves pried off the front headlight of a friend’s Toyota, and managed to steal it just by saying the right things into the network. Since the headlight is on the same network as the door locks, pulling out the bulb and sending the “open the door” message repeatedly, along with a lot of other commands to essentially jam some other security features, can pull it off.
Half of you are asking what this has to do with Arthur C. Clarke, and the other half are probably asking what a lightbulb is doing on a car’s data network. In principle, it’s a great idea to have all of the electronics in a car be smart electronics, reporting their status back to the central computer. It’s how we know when our lights are out, or what our tire pressure is, from the driver’s seat. But adding features adds attack surfaces. What seems like magic to the driver looks like a gold mine to the attacker, or to car thieves.
With automotive CAN, security was kind of a second thought, and I don’t mean this uncharitably. The first goal was making sure that the system worked across all auto manufacturers and parts suppliers, and that’s tricky enough. Security would have to come second. And more modern cars have their CAN networks encrypted now, adding layers of magic on top of magic.
But I’m nearly certain that, when deciding to replace the simple current-sensing test of whether a bulb was burnt out, the engineers probably didn’t have the full cost of moving the bulb onto the CAN bus in mind. They certainly had dreams of simplifying the wiring harness, and of bringing the lowly headlight into the modern age, but I’d bet they had no idea that folks were going to use the headlight port to open the doors. Sufficiently advanced tech.
