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Its not really vendor locking by design. It locks to a signing key. That key COULD be shared between vendors or even a single vendor could have multiple incompa
by jlawer 6y ago
Its not really vendor locking by design. It locks to a signing key. That key COULD be shared between vendors or even a single vendor could have multiple incompatible keys.
It provides a mechanism to prove the entire boot process hasn't been tampered with, but I wish AMD provided a way to run these fused processors in a generic way without the security chain, with it just reporting that there isn't a secure root of trust. However I assume they are afraid of that allowing malicious code to fool deeper parts of the system without the system administrator knowing.
So good for security, but bad for e-waste and second hand sales.
- 3np 6y agoWouldn’t it make more sense to blow the motherboard rather than the CPU? A compromised CPU without anything connected is pretty useless at boot. The motherboard is what’s connected to all the good stuff.
- 0zymandiass 6y agoThe CPU isn't what's compromised - this is protecting against a compromised motherboard
- soneil 6y agoI think that’s the chicken & egg. If the motherboard was responsible for this, you’re trusting the firmware to validate itself. So this moves the validation a level lower. It’s an interesting problem. The solution is valid, but it’s unfortunately permanent.
- im3w1l 6y agoYou could have a small rom firmware validating a larger ugradable firmware.
- bayindirh 6y agoHowever, the root of trust is embedded to the CPU. So, you can't hammer the CPU on another board for keys. Also, we sometimes lose the CPU rather than the board. As the CPUs become more complex, their probability to fail has risen.
- 3np 6y ago> However, the root of trust is embedded to the CPU. So, you can't hammer the CPU on another board for keys. I guess that's the key point here.
- tyingq 6y agoIs there any guarantee each vendor will only ever use one signing key? Or might we have problems swapping from one Dell to another Dell, for example?
- Patrick-STH 6y agoDiscussed later in the video. But this is possible which adds another layer of complexity if one tries to track pulls.
- necovek 6y agoI would imagine they'd have to use new ones every once in a while. What I am most worried about is vendor's key becoming compromised (whether cracked or stolen), which means that a revocation mechanism is missing. Even with revocation implemented, such equipment would be rendered useless (I imagine vendor would have to cover for replacements).
- crdrost 6y agoWould be interesting to know whether Dell will use the signing key to unlock the CPU if you ship it to them, or if it's like old motherboards where there is a physical procedure (it was typically to powercycle with a jumper between two pins that shouldn't normally be joined) to reset it, built into the hardware. Seems strange to be able to "brick" a CPU like that.
- soneil 6y agoThe article describes the mechanism as programmable fuses; so there is a near-certain chance these are one-time-programmable and can’t be reset. Ever. (This is fairly normal in cpus. Picture 8 regular fuses. If you read across them, you’ll get 0xff. Now blow the first four fuses and read again. You’ll get 0xf0. Here’s the catch. You can’t “unblow” them. With real fuses, you’d replace them. If they’re inside the cpu, you replace the cpu.) Fun trivia. The boot loader signing in the raspberry pi works the same way.
- mywittyname 6y agoThe XBox 360 used the same technique for patches to keep you from downgrading the system.
- vii 6y agoSame for the Nintendo Switch. Older firmware has exploits, which allow installing Ubuntu, etc. To prevent exploiting, old firmware refuses to boot if the new firmware has ever booted. This is marked by blowing fuses. Note - there is even a fuse that when blown, prevents other fuses from being blown! https://docs.nvidia.com/jetson/archives/l4t-archived/l4t-3231/index.html#page/Tegra%20Linux%20Driver%20Package%20Development%20Guide/bootloader_secure_boot.html https://docs.nvidia.com/jetson/archives/l4t-archived/l4t-323...
- strombofulous 6y agoIs there a downside to blowing that anti-blow fuse? Can its state be read?
- shawnz 6y agoWhy couldn't they have put the key in user-resettable memory which erases the disk encryption key when cleared, like with TPMs for example? It was a poor design to even allow it to be used this way.
- sterlind 6y agoBooting from disk is the BIOS's job. The whole point is to guard against a compromised motherboard.
- shawnz 6y agoIf the CPU prevents the disk from ever being unlocked, there's nothing to compromise by controlling the motherboard
- clinta 6y agoThis method prevents the user from trying to recover with a backed up encryption key, or booting live media. Instead it makes it clear that this motherboard is compromised and cannot be safely used.
- shawnz 6y agoAnd in the current model, what prevents the user from assuming the processor is dead and replacing it with an unlocked one (which will then presumably become permanently locked to the compromised motherboard)? If you care about this specific attack scenario then make sure you check the keys with a management tool or something. It's not necessary to make the chip unusable for almost every aftermarket user just to make it a little bit clearer that a compromise has happened in that rare case.
- clinta 6y agoFair point. Though in many large environments the number of people with access to the IPMI console is greater than the number of people with physical access who can swap out a CPU. I'm just trying to speculate what might be driving demand for this type of feature, since TPMs already exist.
- Abishek_Muthian 6y ago>So good for security, but bad for e-waste and second hand sales I concur, but it's true for even consumer devices like smartphones. Once the software updates stop, if security is the key then the devices are e-waste. Many times, I wish there was an International law which forces manufacturers to unlock their device when they stop pushing software updates to their device, so that alternate firmware can be installed. Of course this is just a wishful thinking, even those who abandoned their smartphone segment entirely(MS) didn't do this, So why would those who run profitable business out of planned obsolescence do it?
- xwdv 6y agoIt almost seems that a law like that would be something out of a sci-fi or cyberpunk universe.
- Abishek_Muthian 6y agoMarginalised people living among e-waste in every Cyberpunk universe is already true anyways.
- ajuc 6y agoWe live in a cyberpunk universe. The only think it got wrong was aesthetic.
- swiley 6y agoInstead of grunge everything is covered in RGB LEDs. Literally almost everyone my age has RGB LEDs everywhere. All over their rooms and not to mention keyboards.
- theandrewbailey 6y agoBright neon-colored lighting is a big part of the cyberpunk aesthetic.
- ornornor 6y ago
- segfaultbuserr 6y ago> Its not really vendor locking by design. It locks to a signing key. I see, so it's basically AMD's implementation of Intel Boot Guard, but on servers instead of laptops. On boot, the CPU verifies the BIOS's signature from its OTP memory and refuses to boot if verification fails. Theoretically, if you move CPUs between different laptops, you'll find the CPUs are locked to its platform as well, but we don't feel it since they are not replaceable, the only visible effect is that the firmware has been locked and you cannot run coreboot. And now the same thing is coming to servers and it has a bigger visible effect...
- throwaway2048 6y agoIt is designed to destroy the secondhand market, the fact it can be hand waved away as "security" is just the smokescreen. It could be implemented in a way that preserves the ability to reuse CPUs, but it wont be.
- rocqua 6y agoWhat would such an alternative implementation be?
- tyingq 6y agoI guess they could provide a key that works with all the fuses blown, and a utility to blow all of them.
- Sebb767 6y agoIn which case you could easily blow all fuses, sign your malicious firmware with the all-fuses key and you're good to go.
- R0b0t1 6y agoNo, this won't work if the user is checking the attestation ability of the firmware or system. A similar exploit already exists by just modifying the firmware and expecting the user the just replace the CPU without checking the BIOS.
- deleted 6y ago[deleted]
- bubblethink 6y ago>So good for security This is entirely debatable. This is essentially bootguard for socketed CPUs similar to how most laptops behave. For one, it makes fixing the crap that Dell and their contractors write impossible. You cannot replace the bios with coreboot. For all these features that require blessings, I really liked apple's use of the term notarised. Everyone should call these notarisation features rather than security ones. It's as boring and useless as going to a notary, if you have ever done that.
- josh2600 6y agoNotarization is good. Intel calls enclave signing “attestation”, which is clear to me.