ESET researchers discovered 11 vulnerable UEFI shim bootloaders signed by Microsoft that allow attackers to bypass UEFI Secure Boot by exploiting decade-old vulnerabilities.
The difference is that with ARM TrustZone, there is an efuse burned with the key that the manufacturer set in the SoC itself that checks the signature of the primary bootloader, which cannot be modified.
Standard computers do not have such a hardware-level key, so if you wanted to replace the bootloader with something like coreboot if it has been ported to your board, then you can. On smartphones, you do not have that option.
Same thing goes for even more locked down systems like game consoles.
Is there no way to clear that memory? Or is it more just that it’s uncommonly difficult that the people with the skillset just do other, more value added things?
It’s not memory, but rather physical fuses that have been blown on the die itself, similar to the Xbox 360’s downgrade protection fuses and CPU key. Much like the Xbox 360, the only way to bypass it would be to do something like a reset glitch hack to glitch the state of the CPU right as it tries to read the state of the fuses and bypass that check, and that would require a specific modchip for every individual device. Another option would be to replace the SoC with one that does not have that protection enabled to begin with.
Yeah. Best to look out for devices that don’t have this restriction. Not 100% sure if the Fairphone and Shiftphone have this, but I’m sure if you ask them, they’ll tell you.
The difference is that with ARM TrustZone, there is an efuse burned with the key that the manufacturer set in the SoC itself that checks the signature of the primary bootloader, which cannot be modified.
Standard computers do not have such a hardware-level key, so if you wanted to replace the bootloader with something like coreboot if it has been ported to your board, then you can. On smartphones, you do not have that option.
Same thing goes for even more locked down systems like game consoles.
Ah, that makes a lot more sense!
Is there no way to clear that memory? Or is it more just that it’s uncommonly difficult that the people with the skillset just do other, more value added things?
It’s not memory, but rather physical fuses that have been blown on the die itself, similar to the Xbox 360’s downgrade protection fuses and CPU key. Much like the Xbox 360, the only way to bypass it would be to do something like a reset glitch hack to glitch the state of the CPU right as it tries to read the state of the fuses and bypass that check, and that would require a specific modchip for every individual device. Another option would be to replace the SoC with one that does not have that protection enabled to begin with.
I was unaware of this. Super interesting, and disturbing honesty.
Yeah. Best to look out for devices that don’t have this restriction. Not 100% sure if the Fairphone and Shiftphone have this, but I’m sure if you ask them, they’ll tell you.
I think the nothing phone does not have it, at least, i doubt because their bootloader is not locked IIRC
Having an unlockable bootloader is a separate thing from being able to replace the primary bootloader entirely.
My bad, i misunderstood