A team of Chinese researchers has described the analysis process that resulted in the discovery of 19 vulnerabilities in a Mercedes-Benz E-Class, including flaws that can be exploited to remotely hack a car.
The research was conducted starting in 2018 by Sky-Go, the vehicle cybersecurity unit of Chinese security solutions provider Qihoo 360. The findings were disclosed to Daimler, which owns the Mercedes-Benz brand, in August last year. The car maker patched the security holes and in December 2019 it announced that it had joined forces with the Sky-Go team in an effort to improve the security of its vehicles.
Representatives of Sky-Go and Daimler disclosed the findings this week at the Black Hat cybersecurity conference and published a research paper detailing the findings. However, some information was not made public to protect Daimler’s intellectual property and to prevent malicious exploitation.
The researchers conducted their analysis on a real Mercedes-Benz E-Class and demonstrated how a hacker could have remotely unlocked the car’s doors and started its engine. The experts estimated that the vulnerabilities could have impacted 2 million vehicles in China.
Sky-Go said it targeted the E-Class, which Mercedes describes as the most intelligent business saloon, for its infotainment system, which has the most connectivity functionalities.
The researchers disassembled the center panel and analyzed the car’s head unit, telematics control unit (TCU), and the backend.
In the file system of the vehicle’s TCU, to which they gained access by obtaining an interactive shell with root privileges, they uncovered passwords and certificates for the backend server.
“The car backend is the core of connected cars,” the researchers explained. “As long as the car backend’s services can be accessed externally, it means that the car backend is at risk of being attacked. The vehicles connecting to this car backend are in danger, too.”
They ultimately gained some access to backend servers after analyzing the vehicle’s embedded SIM (eSIM) card, which is typically used to provide connectivity, identify a car, and encrypt communications.
The problem was that backend servers did not authenticate requests from the “Mercedes me” mobile app, which allows users to remotely manage the vehicle and control various functions. Once they got access to the backend, they could control any car in China, the researchers claimed.
A hacker could have exploited this vulnerability to remotely lock and unlock the doors, open and close the roof, activate the horn and lights, and in some cases even start the engine. The researchers said they did not manage to hack any critical safety functions.
A majority of the 19 vulnerabilities discovered by the Sky-Go team affected the TCU and the backend, with a handful found in the head unit and other components. Some of the TCU flaws have been assigned CVE identifiers.