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by snailmailman 695 days ago
I’ve had so many issues with secure boot on my machines causing issues that if I ever saw a secure boot error message I would never think “oh I must have a rootkit”

Instead I would assume, in order

- my config broke it

- OS update broke it

- the bios doesn’t properly handle any case that isn’t “preinstalled OEM windows”

I had a laptop that as far as I could tell, could only boot into windows’ default bootmgr.efi. I could turn off secure boot, and tamper with that efi to boot Linux, but it refused to acknowledge other boot loaders from within the bios. It wouldn’t surprise me in the slightest if secure boot isn’t properly handled. I’ve had too many issues with cheap computers having janky bioses.

2 comments

I feel many security researchers like to overemphasize the importance of certain security practices (the most common one being "longer and random password with symbols and upper case letters") without considering its costs, trouble, and human's lazy nature. Forcing long passwords causes people to use repetitive or easy to remember words, enforcing Secure Boot doesn't work if it gets in the way of normal boots. Making sure that these security mechanisms "just work" is as important as enforcing rules like these.

A natural question is whether Secure Boot is the right place to protect against the type of attack mentioned in the post. Given that we've already invested a lot of effort in fixing kernel privilege escalations, and any program able to install BIOS rootkits can access all data and modify any program anyway, what justifies the extra complexity of Secure Boot (which includes all the extra design necessary to make it secure, such as OS'es robust to tampering even with kernel privileges)? I mean, why invest so much in Secure Boot when you could harden your kernel to prevent tampering BIOS in the first place?

Real security researchers know that requiring symbols and upper case letters actually reduces security. Those requirements are explicitly rejected by the latest NIST recommendations:

https://pages.nist.gov/800-63-3/sp800-63b.html

So I'm basically agreeing with you, that a lot of people "in security" are just cargo culting.

For me it cannot be justified. A corporate environment might be different though.

Still, as a consumer I reject it for personal use because I believe boot malware is rare since other forms of attack have been vastly more effective and I also don't have an evil maid.

I just hope we don't get to a ridiculous situation where my shitty bank gets panic if I root my phone and wants to extend that behavior to PCs. "Trusted computing" is a failure in my opinion and "security" on mobile devices is an example where it significantly impacts the usefulness of the devices themselves. Of course this might be more driven by ambitions to lock down phones than real security, but still.

Secure boot might be useful for devices you administer remotely. But any secure boot validation doesn't mean anything to me, the system could be infected without secure boot noticing anything. It probably only gets in the way of OS installations.

The idea is to stop you getting rootkits that can never be removed. You want to feel safe knowing you can just wipe your computer and start again.
You can usually flash BIOS while wiping your computer in the same way that a malware does except in very rare cases. Also Secure Boot doesn't remove the kind of rootkit that doesn't get removed along with the storage since it has to boot from your hard drive anyway.
Was this laptop in question from Hewlett Packard (HP)? Because I swear I've seen this exact behaviour on a HP laptop.