> The root cause of this bug, once again, lies in the unsafe handling of NVRAM variables.
Sheer incompetence, in other words.
Sheer incompetence, in other words.
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.
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.
I've seen enough examples of that, to suspect there's some truth to it, and wonder why that is...
Speculation:
* Systems programming is hard, and systems programmers who are familiar enough with the kind of target hardware are even more rare. A company might decide to hire a hardware engineer who can code, rather than a systems programmer software engineer who knows enough hardware.
* Hardware companies know hardware, and might have hardware engineers as execs and managers, so they probably know how to hire hardware engineers, but maybe not software engineers.
* Hardware companies respect hardware engineers, and not so much software people. You don't need all those hard math and engineering classes to be a "coder". Even their 12yo can make an app, but you usually need a team with a ton of hardware education and experience to produce a viable board or IC. ("Coding" even sounds like a tedious but straightforward clerical task.)
Other speculation, or does anyone know?
Better software doesn't sell more hardware. From those companies' point of view, what matters is hardware features to make consumers want the product, and manufacturing efficiency to make margins high. The quality of what's in the ROM is no more important than the quality of the fans, servos, DACs or what have you. As long as the parts don't break too often and are within specifications, they're good enough, no point in wasting money to make them better.
This, of course, is true until it isn't. At some point, somebody comes along who disrupts the space completely by making the software great and well integrated (or just by making it do what people have previously had to do in hardware), and traditional companies don't know how to cope.
Same person thinks I'm literally paranoid for splitting home, IoT, and Security cameras into separate networks... despite the cameras and dvr being the banned/recalled costco ones.
https://nvd.nist.gov/vuln/detail/cve-2018-6242
and
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.
Now, Intel platforms you maybe have a shot at using EDK2 on, especially those with FSP. But Intel is unlikely to give you any support when something goes wrong and there’s probably no way to pay Intel to change that unless you’re a very big customer.
[0] https://github.com/openSIL/openSIL
The former decision is made by engineers, the latter by bean counters.
i would argue every apple macbook purchase implicitly includes this.
Lemon market: https://www.sfu.ca/~wainwrig/Econ400/akerlof.pdf
Buyers can't distinguish good work from bad, so they pay only average price and thereby drive out the high-quality sellers.
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.
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.
For your own personal machine, sure. But say you're a sysadmin in a company that has thousands of units. Suddenly, a CA infrastructure is much more appealing than having to deal with component hashes.
Also, the concern is that the system comes from the factory with private keys the owner doesn't have access to, allowing the device to defect by informing on them to a third party. Keys installed by the owner rather than the manufacturer are fine, and then such keys also wouldn't be trusting random third party code either.
With your private CA you can skip the "update the hash" part, removing a crucial step that one might forget in a hurry or that simply might go wrong because of whatever sort of bug or power outage... and brick thousands of machines as a result.
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.
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.
All TPMs have private keys from the factory. They're entirely unrelated to the secure boot keys.
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.
> 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.
TPMs have private keys, and are not involved in enforcing secure boot. The firmware validating the signatures only has public keys.
Isn't that kind of pointless?
Suppose the attacker gets root on your OS, i.e. what they would need to supply the firmware with a new hash. That OS install is now compromised, because they can now change whatever else they want in the filesystem. If you boot the same OS again, even using the trusted bootloader, it's still compromised.
If you don't realize that it's compromised, you're now using a compromised system regardless of the bootloader. If you do realize it's compromised then you do a clean reinstall of the OS and designate your bootloader as the trusted one again instead of whatever the compromised OS installed.
What does the bootloader really get them that root didn't already?
> The firmware validating the signatures only has public keys.
Having the keys installed from the factory still seems like the thing causing the problem:
If it only trusts e.g. Microsoft's public key, they now get to decide if they want to sign something you might want to use. If they don't, secure boot prevents it from working, which causes problems for you if you want it to work.
Which then puts them under pressure to sign all kinds of things because people want their firmware updaters etc. to work, and then you get compromised by some code they signed which wasn't even relevant to you.
Whereas what you want is some way of designating what can run on your machine, regardless of what someone else would like to run on theirs. But then that's a machine-specific determination rather than something somebody should be deciding globally for everyone.