On 12/17/2017 03:23 PM, 'Chris' via qubes-users wrote:

It seems as if Qubes OS is useless in protecting against hardware access. Even with TPM, I am not sure how realistic it is. Will AEM be triggered when changing USB controllers or adding hostile USB devices to the one whilelisted controller that manages the AEM device? If not, what is the point of AEM? How is AEM any better than simply putting the bootloader on a separate disk? Okay, it gives a bit better piece of mind that really MY bootloader was used, but that is about it, right? It won't help against someone adding compromised devices to a PCI-E slot or USB?!

Any links or help here? Btw, its really hard to find any useful information via Google about most topics regarding Qubes OS. Is Qubes OS somehow downranked intentionally?

Welcome to Qubes, circa 2012. :)

If you dig into old listgroup posts, you'll see this topic covered over and over again. Much of the discussion is based-on or references Joanna's (@rootkovska) blog posts:

https://blog.invisiblethings.org/index.html

TL;dr - AEM protects you only within a margin where an attacker (e.g. Evil Maid) isn't terribly skilled and has only a brief window of time to attack. Beyond that, we are *still* talking about physical access here.

Another data point is the HCL. If you look for entries by "Qubes core developers" you should notice all of those systems are Laptops! Qubes is rather laptop-centric because they are more integrated and more difficult to subvert in a piecemeal fashion. IIRC Joanna has recommended PC laptops as preferable because of keyboards that are not only integrated, but also PS/2 (non-USB).

Add to that a sprinkling of discussion about making motherboards more tamper-evident.

So there is a certain level of pragmatism when it comes to physical security. The fact that Qubes was released for PC hardware should not be taken as a sign that the Qubes community regards current PC architecture as having very good security. Qubes tries to make the best out of a bad situation, and even the core devs want better-designed hardware.

Finally, there is the notion that if someone is resourceful enough to trick your TPM, then "you probably have bigger problems than PC security anyway". Its sort of an infosec cop-out, but there's some truth to it.

--

Chris Laprise, [email protected]
https://github.com/tasket
https://twitter.com/ttaskett
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