4 ms·

> The root cause of this bug, once again, lies in the unsafe handling of NVRAM variables. Sheer incompetence, in other words.

by db48x 1y ago

candiddevmike 1y ago
This is all too common with any kind of user infantilizing security feature. Trust us bro, it's secure.
- ahepp 1y ago
  I'm not sure I understand why secure boot is user-infantilizing? I think there are some legitimate concerns about where attestation could be headed, but I like the ability to force my machine to only run signed executables. It seems like the immediate problem here is that most people will never enroll their own keys, and if every vendor's crappy EFI binary gets signed by Microsoft, there will be a huge library of garbage vendor code which is all an attack surface.
  - AnthonyMouse 1y ago
    The problem here is that the signature doesn't do anything for you. Suppose you want to be assured of the software running on your machine. You go into the firmware, point it at your boot loader and say "only this one". It makes a hash of the boot loader and refuses to use any other one until you change the setting, which requires your firmware password. Your boot loader then only loads the operating systems you've configured, and so on. That doesn't require any certificates and you get 100% of the benefits. The firmware needs to verify the boot loader and the boot loader the OS etc. The OS doesn't need to verify the firmware because it can't because if the firmware or boot loader was compromised then the code in the OS to validate it would be just as compromised. The only thing the signature gets you is remote attestation, which is the evil to be prevented. Simple hashing would get you everything else. And then you also don't get this "garbage code is nonetheless trusted" problem because there is no global root of trust and you never told your firmware to trust this random firmware update utility for somebody else's hardware.
    - gruez 1y ago
      >Suppose you want to be assured of the software running on your machine. You go into the firmware, point it at your boot loader and say "only this one". It makes a hash of the boot loader and refuses to use any other one until you change the setting, which requires your firmware password. Your boot loader then only loads the operating systems you've configured, and so on. What if you need to update the bootloader? >The only thing the signature gets you is remote attestation, which is the evil to be prevented. Simple hashing would get you everything else. TPMs can do remote attestation without signatures just fine, by measuring the hash of the bootloader. It'd be clumsy, but doable, just like your idea of using hashes for verification.
      - AnthonyMouse 1y ago
        > What if you need to update the bootloader? Then you boot the system from the existing bootloader, causing the booted system to be trusted to supply a new hash. > TPMs can do remote attestation without signatures just fine, by measuring the hash of the bootloader. If there are no private keys in the TPM from the factory then there is nothing for a third party to force you to sign the hash with, as intended.
        mjg59 1y ago
        How does the system know whether the new bootloader is legitimate or not? All TPMs have private keys from the factory. They're entirely unrelated to the secure boot keys.
        AnthonyMouse 1y ago
        > How does the system know whether the new bootloader is legitimate or not? However it wants to. Maybe the existing bootloader (chosen by the owner rather than the vendor) or the OS it loads has its own signature verification system for update packages, like apt-get. Maybe the OS downloads it from a trusted URL via HTTPS and relies on web PKI. Maybe it uses Kerberos authentication to get it from the organization's own update servers. Maybe it just boots an OS that allows the operator to apply any update they want from a USB stick, but only after authenticating with the OS. None of that is the firmware's problem, all it has to do is disallow modifications to itself unless the owner has entered the firmware password or the system is booted from the owner-designated trusted bootloader. > All TPMs have private keys from the factory. They're entirely unrelated to the secure boot keys. The point isn't which device has the keys, it's that it shouldn't contain any from the factory. Nothing good can come of it.
OjotCewIo 1y ago
UEFI variables or not: who in their right mind serializes raw pointer values to any kind of storage (network, disk, nvram, ...)? Why is it that the most security-sensitive areas are ravaged by the sloppiest programmers and the most negligent managers and business types? I'd like to understand the economics and the psychology behind it.
- gmueckl 1y ago
  Security is competing with all other requirements that a product has. That's all there is to it.
- EPWN3D 1y ago
  They're not. They're ravaged by probably the same quality or slightly higher than average. The cost of mistakes is just way higher.
- db48x 1y ago
  It’s something about hardware companies writing software. The motherboard itself may be excellent, but the BIOS/UEFI/ACPI tables will be horrible. Meanwhile you look at a company like Oxide that is a software company at heart, and their equivalents are so much better. Like someone actually designed it so that when humans write the software it will still be secure.
  - bradfa 1y ago
    I have a ton of respect for what Oxide did by not using an off the shelf firmware for their Epyc chips. But unless you’re them, AMD is going to send any small customer to Insyde to buy their UEFI and AMD is not going to give you the kind of access and info that normal engineering teams would expect to get in order to implement their own firmware for Zen based Epyc chips. Most small customers have no choice but to buy a preexisting firmware from an IBV and you get all their security bugs included. You’re lucky if you get full source code and it actually compiles. This is the state of our industry today.
    - wmf 1y ago
getcrunk 1y ago
Yea but when things like this keep happening … it becomes a pattern. A very convenient one at that.
eukara 1y ago
or they have read the Simple Sabotage Field Manual.

> The root cause of this bug, once again, lies in the unsafe handling of NVRAM variables. Sheer incompetence, in other words.

by db48x 1y ago

> The root cause of this bug, once again, lies in the unsafe handling of NVRAM variables. Sheer incompetence, in other words.

candiddevmike 1y ago

This is all too common with any kind of user infantilizing security feature. Trust us bro, it's secure.

ahepp 1y ago
I'm not sure I understand why secure boot is user-infantilizing? I think there are some legitimate concerns about where attestation could be headed, but I like the ability to force my machine to only run signed executables. It seems like the immediate problem here is that most people will never enroll their own keys, and if every vendor's crappy EFI binary gets signed by Microsoft, there will be a huge library of garbage vendor code which is all an attack surface.
- AnthonyMouse 1y ago
  The problem here is that the signature doesn't do anything for you. Suppose you want to be assured of the software running on your machine. You go into the firmware, point it at your boot loader and say "only this one". It makes a hash of the boot loader and refuses to use any other one until you change the setting, which requires your firmware password. Your boot loader then only loads the operating systems you've configured, and so on. That doesn't require any certificates and you get 100% of the benefits. The firmware needs to verify the boot loader and the boot loader the OS etc. The OS doesn't need to verify the firmware because it can't because if the firmware or boot loader was compromised then the code in the OS to validate it would be just as compromised. The only thing the signature gets you is remote attestation, which is the evil to be prevented. Simple hashing would get you everything else. And then you also don't get this "garbage code is nonetheless trusted" problem because there is no global root of trust and you never told your firmware to trust this random firmware update utility for somebody else's hardware.
  - gruez 1y ago
    >Suppose you want to be assured of the software running on your machine. You go into the firmware, point it at your boot loader and say "only this one". It makes a hash of the boot loader and refuses to use any other one until you change the setting, which requires your firmware password. Your boot loader then only loads the operating systems you've configured, and so on. What if you need to update the bootloader? >The only thing the signature gets you is remote attestation, which is the evil to be prevented. Simple hashing would get you everything else. TPMs can do remote attestation without signatures just fine, by measuring the hash of the bootloader. It'd be clumsy, but doable, just like your idea of using hashes for verification.
    - AnthonyMouse 1y ago
      > What if you need to update the bootloader? Then you boot the system from the existing bootloader, causing the booted system to be trusted to supply a new hash. > TPMs can do remote attestation without signatures just fine, by measuring the hash of the bootloader. If there are no private keys in the TPM from the factory then there is nothing for a third party to force you to sign the hash with, as intended.
      - mjg59 1y ago
        How does the system know whether the new bootloader is legitimate or not? All TPMs have private keys from the factory. They're entirely unrelated to the secure boot keys.
        AnthonyMouse 1y ago
        > How does the system know whether the new bootloader is legitimate or not? However it wants to. Maybe the existing bootloader (chosen by the owner rather than the vendor) or the OS it loads has its own signature verification system for update packages, like apt-get. Maybe the OS downloads it from a trusted URL via HTTPS and relies on web PKI. Maybe it uses Kerberos authentication to get it from the organization's own update servers. Maybe it just boots an OS that allows the operator to apply any update they want from a USB stick, but only after authenticating with the OS. None of that is the firmware's problem, all it has to do is disallow modifications to itself unless the owner has entered the firmware password or the system is booted from the owner-designated trusted bootloader. > All TPMs have private keys from the factory. They're entirely unrelated to the secure boot keys. The point isn't which device has the keys, it's that it shouldn't contain any from the factory. Nothing good can come of it.

OjotCewIo 1y ago

UEFI variables or not: who in their right mind serializes raw pointer values to any kind of storage (network, disk, nvram, ...)? Why is it that the most security-sensitive areas are ravaged by the sloppiest programmers and the most negligent managers and business types? I'd like to understand the economics and the psychology behind it.

gmueckl 1y ago
Security is competing with all other requirements that a product has. That's all there is to it.
EPWN3D 1y ago
They're not. They're ravaged by probably the same quality or slightly higher than average. The cost of mistakes is just way higher.
db48x 1y ago
It’s something about hardware companies writing software. The motherboard itself may be excellent, but the BIOS/UEFI/ACPI tables will be horrible. Meanwhile you look at a company like Oxide that is a software company at heart, and their equivalents are so much better. Like someone actually designed it so that when humans write the software it will still be secure.
- bradfa 1y ago
  I have a ton of respect for what Oxide did by not using an off the shelf firmware for their Epyc chips. But unless you’re them, AMD is going to send any small customer to Insyde to buy their UEFI and AMD is not going to give you the kind of access and info that normal engineering teams would expect to get in order to implement their own firmware for Zen based Epyc chips. Most small customers have no choice but to buy a preexisting firmware from an IBV and you get all their security bugs included. You’re lucky if you get full source code and it actually compiles. This is the state of our industry today.
  - wmf 1y ago

getcrunk 1y ago

Yea but when things like this keep happening … it becomes a pattern. A very convenient one at that.

eukara 1y ago

or they have read the Simple Sabotage Field Manual.