Recently two researchers working with a Wired Magazine reporter have demonstrated a serious vulnerability in UConnect, the software that powers the onboard entertainment systems of all Chrysler group cars manufactured after 2013: http://www.wired.com/2015/07/hackers-remotely-kill-jeep-highway/
This does sound scary, but in the article it is stated that
Uconnect’s cellular connection also lets anyone who knows the car’s IP address gain access from anywhere in the country.
which is quite logical, I need to know where to send my payload, but doesn't this decrease the severity of the attack by orders of magnitude? It isn't easy to get a particular car's IP, definitely without physical access, and that's assuming it's constant, which it likely isn't since it's using cellular connectivity. Apparently the car belonged to one of the researchers, so I imagine they found out what the IP was before performing the attack.
Am I missing something? Is it easier than I think to grab the IP of a car I spot in the street?