Two separate teams of security researchers have published working proof-of-concept exploits for an unpatchable vulnerability in Nvidia’s Tegra line of embedded processors that comes on all currently available Nintendo Switch consoles.
Dubbed Fusée Gelée and ShofEL2, the exploits lead to a coldboot execution hack that can be leveraged by device owners to install Linux, run unofficial games, custom firmware, and other unsigned code on Nintendo Switch consoles, which is typically not possible.
Both exploits take advantage of a buffer overflow vulnerability in the USB software stack of read-only boot instruction ROM (IROM/bootROM), allowing unauthenticated arbitrary code execution on the game console before any lock-out operations (that protect the chip’s bootROM) take effect.
The buffer overflow vulnerability occurs when a device owner sends an “excessive length” argument to an incorrectly coded USB control procedure, which overflows a crucial direct memory access (DMA) buffer in the bootROM, eventually allowing data to be copied into the protected application stack and giving attackers the ability to execute code of their choice.
In other words, a user can overload a Direct Memory Access (DMA) buffer within the bootROM and then execute it to gain high-level access on the device before the security part of the boot process comes into play.
“This execution can then be used to exfiltrate secrets and to load arbitrary code onto the main CPU Complex (CCPLEX) application processors at the highest possible level of privilege (typically as the TrustZone Secure Monitor at PL3/EL3),” hardware hacker Katherine Temkin of ReSwitched, who released Fusée Gelée, said.
However, the exploitation requires users to have physical access to the hardware console to force the Switch into USB recovery mode (RCM), which can simply be done by pressing and shorting out certain pins on the right Joy-Con connector, without actually opening the system.
By the way, fail0verflow said a simple piece of wire from the hardware store could be used to bridge Pin 10 and Pin 7 on the console’s right Joy-Con connector, while Temkin suggested that simply exposing and bending the pins in question would also work.
Once done, you can connect the Switch to your computer using a cable (USB A → USB C) and then run any of the available exploits.
Fusée Gelée, released by Temkin, allows device owners only to display device data on the screen, while she promised to release more scripts and full technical details about exploiting Fusée Gelée on June 15, 2018, unless someone else made them public.
She is also working on customized Nintendo Switch firmware called Atmosphère, which can be installed via Fusée Gelée.
On the other hand, ShofEL2 exploit released by famous fail0verflow team allows users to install Linux on Nintendo Switches.
“We already caused temporary damage to one LCD panel with bad power sequencing code. Seriously, do not complain if something goes wrong,” fail0verflow team warns.
Meanwhile, another team of hardware hackers Team Xecutor is also preparing to sell an easy-to-use consumer version of the exploit, which the team claims, will “work on any Nintendo Switch console regardless of the currently installed firmware, and will be completely future proof.”
Nintendo Can’t Fix the Vulnerability Using Firmware Update
The vulnerability is not just limited to the Nintendo Switch and affects Nvidia’s entire line of Tegra X1 processors, according to Temkin.
“Fusée Gelée was responsibly disclosed to NVIDIA earlier, and forwarded to several vendors (including Nintendo) as a courtesy,” Temkin says.
Since the bootROM component comes integrated into Tegra devices to control the device boot-up routine and all happens in Read-Only memory, the vulnerability cannot be patched by Nintendo with a simple software or firmware update.
“Since this bug is in the Boot ROM, it cannot be patched without a hardware revision, meaning all Switch units in existence today are vulnerable, forever,” fail0verflow says. “Nintendo can only patch Boot ROM bugs during the manufacturing process.”
So, it is possible for the company to address this issue in the future using some hardware modifications, but do not expect any fix for the Switches that you already own.
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