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> To this day, key players in security—among them Microsoft and the US National Security Agency—regard Secure Boot as an important, if not essential, foundation

> To this day, key players in security—among them Microsoft and the US National Security Agency—regard Secure Boot as an important, if not essential, foundation of trust in securing devices in some of the most critical environments, including in industrial control and enterprise networks. Am I correct that Secure Boot purely exists to prevent this attack vector: malware gets root on the OS, hardware allows updating firmware via OS now owned by malware, but Secure Boot means you have to wipe only the hard drive instead of the firmware to eliminate the malware. It seems like it would be a lot simpler and more reliable to add a button to motherboards that resets the firmware to the factory version (on memory that can't be written by a malicious OS).

Terr_ 2y ago
I'm having strange nostalgic flashbacks the '90s where I kept wondering why nobody offered a hard drive with a physical read-only toggle button. (Mounted to the front of the 5.25 inch bay in a tower chassis, as was the style of the time.) Obviously you need some read+write storage elsewhere on the same computer, but you could reliably freeze large chunks of stuff in a way that would be impervious to viruses or hackers.
- CableNinja 2y ago
  There were things like this, but it was more to prevent accidental writes. Some of the old 10" drives had a write enable toggle.
- drhagen 2y ago
  I remember USB drives in the '00s that had a read-only toggle. They were useful for rescuing machines that had a virus. Edit: A quick search reveals that, of course, you can still buy them today. I have not felt a need for one in ages.
  - Terr_ 2y ago
    Hmmm, I would absolutely buy one of those if it also had a hardened case and a firm connection point for my real-world keychain. The use-case is a "my house burned down what next" backup, password-manager stuff and other details I might need before/without accessing any cloud-backup services. I may need to read some of its files on a not-very trusted device, and I don't want to risk that device also tampering/trojan'ing other files, like backup copies of the software needed to decrypt the data files. A simpler scenario might be a USB stick that I use for carrying files to be printed at the local library.
    - deleted 2y ago
      [deleted]
  - Hizonner 2y ago
    I strongly suspect that most or all of the modern "hardware" write-protect switches are actually just suggestions to the drive firmware. Which may very well itself be modifiable.
    - Gormo 2y ago
      I can't imagine how it would be possible to do it any other way for a flash storage device. A mechanical hard drive could at least theoretically have a physical lock attached to the drive head which prevents it from approaching the platters if it is engaged.
      - Hizonner 2y ago
        Erm. The read head and the write head in a magnetic drive are the same head. You can't keep the head away from the surface if you want to read the disk. But you can disable power to the driver that puts write current into the head. ... and you could absolutely build similar functionality into a flash chip. But most likely you can't actually buy such chips, at least not with any real capacity.
        deleted 2y ago
        [deleted]
        mypalmike 2y ago
        There are multi-actuator hard drives out there. I don't know if any of them separate read heads from write heads, but it would certainly seem possible for such a drive to exist.
      - schmidtleonard 2y ago
        Writing flash takes (relatively) high voltage and the voltage boosting circuitry could be routed through a switch. It generally isn't, and the voltage converter is often an on-chip charge pump so this wouldn't be an easy retrofit, but the current state of affairs is due entirely to lack of interest rather than lack of possibility.
  - GuB-42 2y ago
    I have one of these as a boot disk (Medicat) for this exact reason. Also because some of the software included in Medicat is flagged by some anti-virus software and I don't want them removed.
judge2020 2y ago
That sounds correct, but even the savviest of users might not be aware they have malware installed when they decide to re-install windows. If cleaning malware requires pressing a button on the MOBO then I can imagine only a single-digit percentage of users will actually click it.
- Dylan16807 2y ago
  If they're not worried about malware, and there is some, then they'd probably get reinfected by their data anyway.
bitwize 2y ago
Secure Boot is the first component in a verified boot chain from initial power-on to application level code. Signed, verified firmware boots signed, verified kernel with strict authenticity and integrity guarantees. The goal is, presumably, to attest to the authenticity and integrity of everything the system runs, but when it comes to kernel modules and device drivers, userland OS components, and applications, those are the kernel's responsibility. But Secure Boot is an essential link in this chain.
acdha 2y ago
Also things around physical access: if you steal my laptop, FDE prevents you from getting my data immediately but if you install malware which takes over the boot process, you get that data as soon as I type in my password. If the process changes so the hardware only loads signed firmware, which only loads a signed boot loader, which only loads a signed kernel, etc. that avenue of attack is closed. It also makes it possible to trust a used computer. The problem is that other than Apple nobody has really been committed to doing it well - it’s begrudging lowest-bidder compliance and clearly not something many vendors are taking pride in.
- out-of-ideas 2y ago
  do folks in the business really simply steal a laptop and try to pull all data? or do they steal the laptop and wipe it and flip it... if they wanted your data wouldnt they steal you, the human, too ? the signing method only offers buying more time before the innevitable data is "breached" by a theat actor - its the same buying-time for any and all encryption. the system can get too complex, and the underlying problems of humans will always exist (and amplified by more points of failure).. (accidents, data breaches, exploits, ect). the system needs to be immutable, but also mutable at the same time (for updates, ect) - and thats not exactly something easy to accomplish. and with apple.. they try yes, but it is forever a walled garden. we've already seen their secure enclave bloatloader shinanigans get exploited on phones- and it was not fun for those people where their phones were compromised. apple suffer from us humans, too (we will never be perfect, nor will our software)
  - acdha 2y ago
    > do folks in the business really simply steal a laptop and try to pull all data? or do they steal the laptop and wipe it and flip it... if they wanted your data wouldnt they steal you, the human, too ? Governments definitely worry about it, and I’d be shocked if e.g. banks didn’t also put it into requirements. Access can be temporary, too: imagine if you get 15 minute alone in someone’s office or they have a kiosk in the lobby, etc. – not enough time to open the case up but plenty to toss a USB drive in and reboot. Repeat for lost devices or scenarios like the KnowBe4 attack disclosed yesterday where some dude might not be able to explain cracking the case open. > the signing method only offers buying more time before the innevitable data is "breached" by a theat actor - its the same buying-time for any and all encryption. You have to think about cost, too. It appears to be safe to buy a used Mac because Apple employs competent cryptographic engineers and very few targets are worth involving a lab with truly serious hardware. This could be the case on the PC side too, but it’s undercut by vendors skimping on execution and until Secure Boot is pervasive and robust, nobody can easily tell whether hardware they’ve lost control of can be trusted. People have been getting malware on used computers for years and a trusted boot process makes it easier both to tell if that’s happened and to be confident that you’ve fully wiped a system.
tedunangst 2y ago
How do you determine when to push the button?
- jtbayly 2y ago
  Once a day ought to do…
- Dylan16807 2y ago
  Any time you're reinstalling the OS and suspect the old OS had malware. Or if you want to make it simpler, any time you're reinstalling the OS.
- bluescrn 2y ago
  Instead, write-protect the firmware by default, and require the user to press a physical button on the back of the PC to write-enable it (for a limited duration/until the next reboot)
tripflag 2y ago
The case you're outlining (an uefi rootkit) is pretty much the worst case; assuming you get infected by some malware which decides to install a malicious firmware (BIOS update), then pretty much nothing is getting in the way of that. What secureboot is designed to prevent is malicious changes to the OS bootloader (a conventional rootkit), which is usually shimx64.efi or grubx64.efi on linux/dualboot machines, or bootmgfw.efi on windows. Secureboot checks the signature of .efi files before they're allowed to run during boot, ensuring they were signed by one of the trusted keys. And unless you've made changes to your secureboot config, that means microsoft and/or the hardware vendor.
- amluto 2y ago
  I think “UEFI rootkit” usually refers to a malicious .efi file installed in the ESP. An actual firmware rootkit, installed on the flash chip, can likely bypass Secure Boot entirely, and may well be able to bypass TPM protections as well.
gizmo686 2y ago
It is possible to use Secure Boot as part of a fully verified bootchain. The firmware verified the bootloader. The bootloader verifies the kernel (and kernel arguments, and ramdisk...), the kernel verified all executables. Userspace programs verify critical data files. There are systems out there that do this, and having something like Secure Boot is essential to their design (as is measured boot, which is the main mechanism TPMs leverage). However, this solution is utterly unworkable for the personal computer market. Instead, we have a bunch of general purpose kernels signed to run on any computer, but which are willing to run any userspace you through at them.
awaythrow999 2y ago
Immediately gets slapped over the head by the requirement: "preventing downgrade to a vulnerable version" (which would be just a matter of enough time passing)
- antifa 2y ago
  And by "vulnerable version" they mean the version before they added ads to the boot screen.
sim7c00 2y ago
it protects against boot and early boot attacks. thia includes bootkits but also early drivers such as AV drivers and others which protect the system further. if you dont have it, any security can be compromised before its active. via different methods.

Terr_ 2y ago

I'm having strange nostalgic flashbacks the '90s where I kept wondering why nobody offered a hard drive with a physical read-only toggle button. (Mounted to the front of the 5.25 inch bay in a tower chassis, as was the style of the time.) Obviously you need some read+write storage elsewhere on the same computer, but you could reliably freeze large chunks of stuff in a way that would be impervious to viruses or hackers.

CableNinja 2y ago
There were things like this, but it was more to prevent accidental writes. Some of the old 10" drives had a write enable toggle.
drhagen 2y ago
I remember USB drives in the '00s that had a read-only toggle. They were useful for rescuing machines that had a virus. Edit: A quick search reveals that, of course, you can still buy them today. I have not felt a need for one in ages.
- Terr_ 2y ago
  Hmmm, I would absolutely buy one of those if it also had a hardened case and a firm connection point for my real-world keychain. The use-case is a "my house burned down what next" backup, password-manager stuff and other details I might need before/without accessing any cloud-backup services. I may need to read some of its files on a not-very trusted device, and I don't want to risk that device also tampering/trojan'ing other files, like backup copies of the software needed to decrypt the data files. A simpler scenario might be a USB stick that I use for carrying files to be printed at the local library.
  - deleted 2y ago
    [deleted]
- Hizonner 2y ago
  I strongly suspect that most or all of the modern "hardware" write-protect switches are actually just suggestions to the drive firmware. Which may very well itself be modifiable.
  - Gormo 2y ago
    I can't imagine how it would be possible to do it any other way for a flash storage device. A mechanical hard drive could at least theoretically have a physical lock attached to the drive head which prevents it from approaching the platters if it is engaged.
    - Hizonner 2y ago
      Erm. The read head and the write head in a magnetic drive are the same head. You can't keep the head away from the surface if you want to read the disk. But you can disable power to the driver that puts write current into the head. ... and you could absolutely build similar functionality into a flash chip. But most likely you can't actually buy such chips, at least not with any real capacity.
      - deleted 2y ago
        [deleted]
      - mypalmike 2y ago
        There are multi-actuator hard drives out there. I don't know if any of them separate read heads from write heads, but it would certainly seem possible for such a drive to exist.
    - schmidtleonard 2y ago
      Writing flash takes (relatively) high voltage and the voltage boosting circuitry could be routed through a switch. It generally isn't, and the voltage converter is often an on-chip charge pump so this wouldn't be an easy retrofit, but the current state of affairs is due entirely to lack of interest rather than lack of possibility.
- GuB-42 2y ago
  I have one of these as a boot disk (Medicat) for this exact reason. Also because some of the software included in Medicat is flagged by some anti-virus software and I don't want them removed.

judge2020 2y ago

That sounds correct, but even the savviest of users might not be aware they have malware installed when they decide to re-install windows. If cleaning malware requires pressing a button on the MOBO then I can imagine only a single-digit percentage of users will actually click it.

Dylan16807 2y ago
If they're not worried about malware, and there is some, then they'd probably get reinfected by their data anyway.

bitwize 2y ago

Secure Boot is the first component in a verified boot chain from initial power-on to application level code. Signed, verified firmware boots signed, verified kernel with strict authenticity and integrity guarantees. The goal is, presumably, to attest to the authenticity and integrity of everything the system runs, but when it comes to kernel modules and device drivers, userland OS components, and applications, those are the kernel's responsibility. But Secure Boot is an essential link in this chain.

acdha 2y ago

Also things around physical access: if you steal my laptop, FDE prevents you from getting my data immediately but if you install malware which takes over the boot process, you get that data as soon as I type in my password. If the process changes so the hardware only loads signed firmware, which only loads a signed boot loader, which only loads a signed kernel, etc. that avenue of attack is closed. It also makes it possible to trust a used computer. The problem is that other than Apple nobody has really been committed to doing it well - it’s begrudging lowest-bidder compliance and clearly not something many vendors are taking pride in.

out-of-ideas 2y ago
do folks in the business really simply steal a laptop and try to pull all data? or do they steal the laptop and wipe it and flip it... if they wanted your data wouldnt they steal you, the human, too ? the signing method only offers buying more time before the innevitable data is "breached" by a theat actor - its the same buying-time for any and all encryption. the system can get too complex, and the underlying problems of humans will always exist (and amplified by more points of failure).. (accidents, data breaches, exploits, ect). the system needs to be immutable, but also mutable at the same time (for updates, ect) - and thats not exactly something easy to accomplish. and with apple.. they try yes, but it is forever a walled garden. we've already seen their secure enclave bloatloader shinanigans get exploited on phones- and it was not fun for those people where their phones were compromised. apple suffer from us humans, too (we will never be perfect, nor will our software)
- acdha 2y ago
  > do folks in the business really simply steal a laptop and try to pull all data? or do they steal the laptop and wipe it and flip it... if they wanted your data wouldnt they steal you, the human, too ? Governments definitely worry about it, and I’d be shocked if e.g. banks didn’t also put it into requirements. Access can be temporary, too: imagine if you get 15 minute alone in someone’s office or they have a kiosk in the lobby, etc. – not enough time to open the case up but plenty to toss a USB drive in and reboot. Repeat for lost devices or scenarios like the KnowBe4 attack disclosed yesterday where some dude might not be able to explain cracking the case open. > the signing method only offers buying more time before the innevitable data is "breached" by a theat actor - its the same buying-time for any and all encryption. You have to think about cost, too. It appears to be safe to buy a used Mac because Apple employs competent cryptographic engineers and very few targets are worth involving a lab with truly serious hardware. This could be the case on the PC side too, but it’s undercut by vendors skimping on execution and until Secure Boot is pervasive and robust, nobody can easily tell whether hardware they’ve lost control of can be trusted. People have been getting malware on used computers for years and a trusted boot process makes it easier both to tell if that’s happened and to be confident that you’ve fully wiped a system.

tedunangst 2y ago

How do you determine when to push the button?

jtbayly 2y ago
Once a day ought to do…
Dylan16807 2y ago
Any time you're reinstalling the OS and suspect the old OS had malware. Or if you want to make it simpler, any time you're reinstalling the OS.
bluescrn 2y ago
Instead, write-protect the firmware by default, and require the user to press a physical button on the back of the PC to write-enable it (for a limited duration/until the next reboot)

tripflag 2y ago

The case you're outlining (an uefi rootkit) is pretty much the worst case; assuming you get infected by some malware which decides to install a malicious firmware (BIOS update), then pretty much nothing is getting in the way of that. What secureboot is designed to prevent is malicious changes to the OS bootloader (a conventional rootkit), which is usually shimx64.efi or grubx64.efi on linux/dualboot machines, or bootmgfw.efi on windows. Secureboot checks the signature of .efi files before they're allowed to run during boot, ensuring they were signed by one of the trusted keys. And unless you've made changes to your secureboot config, that means microsoft and/or the hardware vendor.

amluto 2y ago
I think “UEFI rootkit” usually refers to a malicious .efi file installed in the ESP. An actual firmware rootkit, installed on the flash chip, can likely bypass Secure Boot entirely, and may well be able to bypass TPM protections as well.

gizmo686 2y ago

It is possible to use Secure Boot as part of a fully verified bootchain. The firmware verified the bootloader. The bootloader verifies the kernel (and kernel arguments, and ramdisk...), the kernel verified all executables. Userspace programs verify critical data files. There are systems out there that do this, and having something like Secure Boot is essential to their design (as is measured boot, which is the main mechanism TPMs leverage). However, this solution is utterly unworkable for the personal computer market. Instead, we have a bunch of general purpose kernels signed to run on any computer, but which are willing to run any userspace you through at them.

awaythrow999 2y ago

Immediately gets slapped over the head by the requirement: "preventing downgrade to a vulnerable version" (which would be just a matter of enough time passing)

antifa 2y ago
And by "vulnerable version" they mean the version before they added ads to the boot screen.

sim7c00 2y ago

it protects against boot and early boot attacks. thia includes bootkits but also early drivers such as AV drivers and others which protect the system further. if you dont have it, any security can be compromised before its active. via different methods.