Re: Well, maybe we should not put software in everything
Why would a sat nav being able to "read speed and steering angle" allow hacker generated car crashes? If the sat nav could in turn control the vehicle's speed or direction then, yes, but otherwise these should just be additional input data streams into the sat nav's system.
If the car just passively broadcast this information without any communication from the sat nav to the car, then fine, but that isn't the usual design philosophy.
A typical architecture is a bidirectional data link where the car receives commands and responds to them. If there is a route to access safety critical systems in the car from anything connected to the Internet (which a sat nav might very well be), you could not be confident that the car could never respond to carefully crafted malign commands. These might do things like interfere with the steering or vehicle speed.
It might not be what the automobile systems designers intended, but building secure systems is extraordinarily hard, and this sort of attack has already been demonstrated, for example https://www.theregister.co.uk/2015/07/21/jeep_patch/
Biting the hand that feeds IT
