Security researchers have discovered a method to jailbreak Tesla’s AMD-based infotainment systems, which effectively unlocks the car’s premium upgrades for free.
The “jailbreak” technique was planned by a team of four, which includes three students from Technische Universität Berlin and an independent researcher.
The team will be presenting their findings at the Black Hat USA 2023 hacker conference in Las Vegas on August 9th.
The upcoming Black Hat 2023 presentation is titled “Jailbreaking an Electric Vehicle in 2023 or What It Means to Hotwire Tesla’s x86-Based Seat Heater.”
The researchers found a vulnerability in the newer AMD-based infotainment systems (MCU-Z) used in modern Tesla models, which allows attackers to unlock restricted vehicle features, such as “Premium Connectivity”, “Acceleration Boost”, and even rear heated seats.
“Tesla has been known for their advanced and well-integrated car computers, from serving mundane entertainment purposes to fully autonomous driving capabilities,” wrote the researchers in Black Hat’s brief summary.
“More recently, Tesla has started using this well-established platform to enable in-car purchases, not only for additional connectivity features but even for analog features like faster acceleration or rear heated seats. As a result, hacking the embedded car computer could allow users to unlock these features without paying.”
Tesla Jailbreak
There are two distinct concerns about the flaw. Firstly, it enables the unpatchable AMD-based “Tesla Jailbreak”, which means that Tesla has no known mitigation solutions to counter it. This flaw allows an attacker to run arbitrary software on the infotainment.
Secondly, the exploit allows the researchers to extract vehicle-unique hardware-bound RSA key, which allows an attacker to authenticate and authorize a car in Tesla’s internal service network.
To activate software-locked features that Tesla car owners normally have to pay for, the researchers used a known voltage fault injection attack against the AMD Secure Processor (ASP), which serves as the root of trust for the infotainment system.
“First, we present how we used low-cost, off-the-self hardware to mount the glitching attack to subvert the ASP’s early boot code. We then show how we reverse-engineered the boot flow to gain a root shell on their recovery and production Linux distribution,” the researchers said.
By gaining root permissions, the researchers were able to make arbitrary changes to Linux that survive reboots and Tesla’s ‘over-the-air’ (OTA) updates.
They were able to decrypt the encrypted NVMe storage and access the owner’s personal data, such as the phonebook, calendar entries, call logs, Wi-Fi passwords, the car’s recent GPS locations, Spotify and Gmail session cookies, and more.
Additionally, the ASP attack opens up the possibility for the attacker to extract a TPM-protected attestation key that Tesla uses to authenticate the car. This enables migrating a car’s identity to another car’s computer.
Besides car ID impersonation on Tesla’s network, it can also benefit car usage in unsupported regions and ease certain repairing and modding efforts, explain the researchers.
While Tesla is yet to make an official statement on the exploit, one of the researchers Christian Werling, told BleepingComputer that they have responsibly disclosed their findings to the car-maker.
“Tesla informed us that our proof of concept enabling the rear seat heaters was based on an old firmware version.
“In newer versions, updates to this configuration item are only possible with a valid signature by Tesla (and checked/enforced by the Gateway).
“So while our attacks lay some important groundwork for tinkering with the overall system, another software or hardware-based exploit of the Gateway would be necessary to enable the rear seat heaters or any other soft-locked feature.”
According to Werling, the RSA key extraction attack can still be exploited in the latest Tesla software update, which is an issue for now.
