Charles Henderson sold his car several years ago, but he still knows exactly where it is, and can control it from his phone. The IBM researcher leading X-Force Red, the firm's security testing group, wasn't researching car security when he discovered a major privacy issue. He simply sold his car. "The car is really smart, but it's not smart enough to know who its owner is, so it's not smart enough to know it's been resold," Henderson told CNNTech. "There's nothing on the dashboard that tells you 'the following people have access to the car.'"
This isn't an isolated problem. Henderson tested four major auto manufacturers, and found they all have apps that allow previous owners to access them from a mobile device. At the RSA security conference in San Francisco on Friday, Henderson explained how people can still retain control of connected cars even after they resell them. Manufacturers create apps to control smart cars — you can use your phone to unlock the car, honk the horn and find out the exact location of your vehicle. Henderson removed his personal information from services in the car before selling it back to the dealership, but he was still able to control the car through a mobile app for years. That's because only the dealership that originally sold the car can see who has access and manually remove someone from the app. A full factory reset of the vehicle doesn't revoke mobile access, Henderson said. In order to revoke app access, you should go to a factory-authorized car dealership.
Source:
http://wtkr.com/2017/02/18/why-buying-used-cars-could-put-your-safety-at-risk/ [wtkr.com]