Sure they could plug a device which sniffs or rewrites CAN frames right into the OBD-II port or the 38 pin port on the Benz. I have done so myself even. I'm not worried about it one bit. Someone would have to specifically want to target me, and if they have access to my car they also have (much easier) access to my house. I am not worried about that either.
Look, if you want to really mess up a car all you need is a pair of needle nose pliers. Locate the brake lines where the hard line meets the soft line going to each caliper, and squash each hard line to crack it just enough that fluid starts to slightly weep out. When the driver first steps on the brakes in earnest the fluid will flow out, and eventually (maybe 5-10 braking events later) the brakes will no longer work.
Again, my threat model does not include someone targeting me specifically. If someone wants to hurt me or vandalize my property they're not gonna do it by writing some esoteric computer program. If you connect your car to the Internet the threat model needs to expand to include "bulk" attacks, which I suspect are actually much more likely.
Look, if you want to really mess up a car all you need is a pair of needle nose pliers. Locate the brake lines where the hard line meets the soft line going to each caliper, and squash each hard line to crack it just enough that fluid starts to slightly weep out. When the driver first steps on the brakes in earnest the fluid will flow out, and eventually (maybe 5-10 braking events later) the brakes will no longer work.
Again, my threat model does not include someone targeting me specifically. If someone wants to hurt me or vandalize my property they're not gonna do it by writing some esoteric computer program. If you connect your car to the Internet the threat model needs to expand to include "bulk" attacks, which I suspect are actually much more likely.