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Purism replies on CHIPSEC failures, adds TPM add-on, starts Heads work

Re: https://firmwaresecurity.com/2017/11/15/purism-librem15-fails-chipsec-security-tests/

Purism responds to the CHIPSEC failures here:

https://forums.puri.sm/t/user-flashable-coreboot-vs-chipsec-security-test-cases/1918

They also point out in that forum, and here:

https://puri.sm/posts/tpm-addon-for-librem-laptops/

that Purism is getting ready to start using Heads payload. They’ve been talking about it for months, maybe it’ll be a real option for upcoming Librem customers? I’m very excited to see a Heads system available by an OEM, instead of DIY and not an easy task.

And they’re adding a TPM as an ‘add-on’ to existing Librem laptops. Heads needs TPM for it’s measurements. (Hmm, I thought TPMs were an integral and tamper-resistant part of the system, and something that could be added on for trust was called a smartcard, but ok. I guess you have to solder the HW to the system. I presume attackers will be ordering spare add-ons so they can swap out units.)

In the above Purism forum, there was this user comment:

“I like the idea of putting a demo Librem notebook to a BlackHat conf where they try to break into the devices. Would be a nice test and a good commercial for you.”

They cannot do that with current Librem models. 🙂 This will need to wait for TPMs to be pre-installed and Heads as the payload.

This response from the above Purism forum seems a bit invalid:

“So there’s no way to access a BIOS menu to change the boot sequence (boot from USB) or set a machine password etc?”

“No, there is no such thing. The BIOS boots into your machine in roughly 450 milliseconds, there is no support for a menu, there is no time even for the user to press a key on the keyboard to enter a menu. The idea of coreboot is to do the minimum hardware initialization and then go to a payload. In our case, we use SeaBIOS which itself will initialize the video card and show the splash screen logo, and wait for 2 seconds for you to press ESC to show you the boot menu and let you choose your device (otherwise, it just boots to the default one). The boot choice isn’t saved, it’s just a boot override. If you want to change an option in coreboot, you need to change the config in the source and recompile coreboot then reflash it. If you want to change the boot order, you need to change the boot order in a file embeded in the flash, then reflash the BIOS.”

Yes, there is thing, which the reply says does not exist then a few sentences later explains that it does exist. The BIOS menu to change the boot order is available to anyone with physical access to the system, and presses the ESC key within 2 seconds of poweron. The unprotected BIOS and MBR-based hard drive can be quickly overwritten with malware on the attacker’s boot thumbdrive. Attendees of ‘a BlackHat conf’ will have such skills. 🙂

Purism is spending all their time undoing Intel’s features — Intel ME, Intel FSP, and now re-embracing older features — Intel TPM. Intel SMM is still an issue, STM is not being used by Purism. Intel ME may be disabled, but it’s a black-box device, who knows when attackers will start reactivating it and putting their malware-based version of Minix on that chip? You’re going to need tools to detect if ME is really disabled. I hope Purism’s roadmap has a RISC-V chip-based laptop in it, so they can stop fighting Intel features and have a fully-open stack. If they keep fighting the Intel stack, I hope they add the ‘stateless laptop’ that Joanna has proposed to their roadmap:

https://blog.invisiblethings.org/2015/12/23/state_harmful.html

It might be useful to add coreboot Verified Boot to help secure their SeaBIOS payload, but that could probably only secure PureOS, and distro hoppers will have no benefit. But I don’t think Heads and Verified Boot are compatible? SeaBIOS also has TPM support, that’d be nice to see those measurements used, if they are embracing a TPM. And now that they have a TPM, they can start using Intel TXT too. 🙂

I am a little perplexed about Purims customer audience, who is concerned about privacy, and yet has so little concern for security, in exchange for the convenience feature of being easy to distro-hop. Anyway, if you want security, wait for the TPM and Heads to be integrated with future Librems.

https://trmm.net/Installing_Heads
https://trustedcomputinggroup.org/
https://puri.sm/products/librem-15/

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