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mjg59I finally managed to get hold of a Thinkpad Z13 to examine a functional implementation of Microsoft's Pluton security co-processor. Trying to boot Linux from a USB stick failed out of the box for no obvious reason, but after further examination the cause became clear - the firmware defaults to not trusting bootloaders or drivers signed with the Microsoft 3rd Party UEFI CA key. This means that given the default firmware configuration, nothing other than Windows will boot. It also means that you won't be able to boot from any third-party external peripherals that are plugged in via Thunderbolt.
There's no security benefit to this. If you want security here you're paying attention to the values measured into the TPM, and thanks to Microsoft's own specification for measurements made into PCR 7, switching from booting Windows to booting something signed with the 3rd party signing key will change the measurements and invalidate any sealed secrets. It's trivial to detect this. Distrusting the 3rd party CA by default doesn't improve security, it just makes it harder for users to boot alternative operating systems.
Lenovo, this isn't OK. The entire architecture of UEFI secure boot is that it allows for security without compromising user choice of OS. Restricting boot to Windows by default provides no security benefit but makes it harder for people to run the OS they want to. Please fix it.
There's no security benefit to this. If you want security here you're paying attention to the values measured into the TPM, and thanks to Microsoft's own specification for measurements made into PCR 7, switching from booting Windows to booting something signed with the 3rd party signing key will change the measurements and invalidate any sealed secrets. It's trivial to detect this. Distrusting the 3rd party CA by default doesn't improve security, it just makes it harder for users to boot alternative operating systems.
Lenovo, this isn't OK. The entire architecture of UEFI secure boot is that it allows for security without compromising user choice of OS. Restricting boot to Windows by default provides no security benefit but makes it harder for people to run the OS they want to. Please fix it.
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no subject
Date: 2022-07-08 10:19 am (UTC)no subject
Date: 2022-07-08 10:38 am (UTC)no subject
Date: 2022-07-08 02:07 pm (UTC)Restricted Boot
Date: 2022-07-08 10:42 am (UTC)Re: Restricted Boot
Date: 2022-07-08 10:49 am (UTC)Re: Restricted Boot
Date: 2022-07-08 01:17 pm (UTC)On the other hand I would turn off Secure Boot anyway because it causes more problems than it solves, which is followed by actually caring about security:
1.) Turn on hardware encryption for the drive
2.) Secure the UEFI with an password
Re: Restricted Boot
Date: 2022-07-08 04:14 pm (UTC)Re: Restricted Boot
Date: 2022-07-12 08:48 pm (UTC)Yes, and this is being used as yet one more step to lock you out of YOUR OWN hardware. Just like more and more other companies out there (hello John Deere, etc).
Re: Restricted Boot
Date: 2022-08-27 04:06 pm (UTC)I don't really see how this is a problem. If you're selling a system with a pre-installed windows and no other components that require the 3rd party CA, there is no reason for it to be trusted by default. Especially when that CA is used to sign pretty much everything and the kitchen sink, and there has been multiple instances in the past of software signed by it either having severe vulnerabilities or outright intentionally booting unsigned code.
If you want to boot something else than what the computer ships with, you can just add the CA in the uefi settings. You probably had to go there to change the boot order anyway, and they even put a magic switch so you don't have to download the CA file yourself. Or even better, put it in custom mode and load your own keys - why would you want to trust microsoft's and the manufacturer's keys if you're not running their code?
Restricted boot would be not allowing to change the keys, this is just tightening security on systems where it's possible.
no subject
Date: 2022-07-08 12:11 pm (UTC)no subject
Date: 2022-07-08 04:16 pm (UTC)no subject
Date: 2022-07-08 01:07 pm (UTC)Bad defaults, bad implementation or bad intention?
Date: 2022-07-08 02:45 pm (UTC)Re: Bad defaults, bad implementation or bad intention?
Date: 2022-07-12 08:53 pm (UTC)MSI are doing the same thing with their latest firmware updates. And there are people on their support site who aren't able to get into the BIOS/UEFI because their video cards won't support it.
(in)Secure Boot has always been a bad idea, as long as a single vendor with every reason to lock everyone else out is the sole gatekeeper. This should ONLY have been handled by an independent body, one that isn't beholden to any party with a personal interest in it. But too many people have been all too happy to just go along with having their rights trampled.
Secure Boot? Really?
Date: 2022-07-08 08:59 pm (UTC)Of course, any tool can be used for good or for evil, depending on who is using the tool, but seriously Mr. Garret: Did you really didn't see that coming?
Of course, the manufacturer is just doing what the owner of the software is asking for, so the manufacturer is not to blame. Even offers a way to bypass the lockdown, but is still something Joe User probably shouldn't care at all.
Security is always a complex issue, but giving the keys to Microsoft was the worst solution to it. But then again, it's not your machine anymore. Not in this age.
Two cents used.
no subject
Date: 2022-07-09 01:21 am (UTC)There are lots of happy mediums. Any company that cares about SCPC will have plenty of other tuning they do to their corporate image so they could easily use a WMI interface to turn off the 3rd party CA at that time.
no subject
Date: 2022-07-09 02:49 am (UTC)Glad you got your hands on a Z13 - as a note, there are some FW fixes coming for fixing a few Linux issues (we haven't finished enablement quite on it yet - but almost there) but it's going to be a Linux certified and supported platform (and I'm personally really liking mine)
For the 3rd party cert - I didn't get a say in this, but the disabling of the 3rd party cert is part of the Microsoft Secured-Core PC certification. You can still enable the cert by going in the BIOS - there is an option to enable it there.
We should have it enabled for our Linux preloaded systems - but it isn't for the Windows preload. You have to toggle it if you want to boot Linux with secure boot enabled.
I don't think this is a Lenovo specific thing - maybe we're the first out with secured-core?
I'll flag your points to the team internally and see if I can get any feedback - when this initially came up my concern was if we'd still be able to boot Linux (and you can).
Mark
no subject
Date: 2022-07-09 05:57 am (UTC)With the chinese you lose
Date: 2022-07-09 09:09 pm (UTC)Re: With the chinese you lose
Date: 2022-07-11 07:49 pm (UTC)Has nothing to do with the nationality of the brand. This has been bog-standard on multiple business laptops for several years now, Secure Boot is on by default. It takes nothing to disable it --I did exactly that to back up my new ThinkPad's original configuration when I got it a week ago before I reloaded it. The second you disable Secure Boot, you boot from any USB key and any OS you want just fine.
This is a feature for corporate laptops, something Dell Latitudes and Precision Mobile Workstations routinely have factory-enabled as well. There's no conspiracy, and your comment above is racist to say the least.
My thoughts
Date: 2022-07-11 12:47 pm (UTC)dbx was always a terrible plan (probably intended for malware/etc that somehow got signed, and legitimate binaries with exploitable bugs weren't considered). Mostly thanks to this, secured core PCs are a joke.
...although I will concede that secured core PCs did one good thing, namely enforcing actual security standards for UEFI firmware.
no subject
Date: 2023-04-16 11:54 pm (UTC)P.S. - Asking for a friend ;)