zlacker

>>jerhei+(OP)
An excellent point that applies to almost any system:

The inconvenient and somehow embarrassing truth for us – the malware experts – is that there does not exist any reliable method to determine if a given system is not compromised.

>>hackus+NI1
This is true for x86-based desktops Qubes targets. You might get past this if you can tolerate a console-like experience with lower-risk hardware. One example is where the state is read-only without physical modification of the machine such as changing a jumper or flipping a switch. Alternatively a combo of ROM and flash where the ROM is immutable but loads signed flash with a correct-by-construction, heavily-pentested module. Apply to various chips in the design. Read-only memory for firmware protection dates back to a mainframe in the 1970's where you had to physically pull old one out and put new one in. OS was built on top of the "Nucleus" API in that for consistency. Microsoft mostly copied that in VerveOS's Nucleus but minus read-only firmware.

An old trick that researchers and implementors should breath more life into. The hardware companies like the more mutable storage for financial reasons. Customers aren't big on replacing hardware but security-focused ones might go with pluggable ROM's long as ROM's aren't changed often. Hence, correct-by-construction approaches that cause few to no defects.

>>nickps+eJ1
Is what you're describing essentially a trust anchor / root of trust, as implemented in TPMs? I realize that TPMs aren't implemented exactly as you describe, but they are designed to be vulnerable only to physical attack, not software attack.

I ignored the (negative) hype and looked into TPMs recently, and I encourage others to do the same.[0] They look like excellent solutions with the important exception that two of the three key hierarchies, the platform hierarchy and endorsement hierarchy, appear to be fundamentally in the vendor's and not in my control (the latter hierarchy can be disabled, as I understand it, but its functionality is then lost). It's surprising that enterprise IT would tolerate that - I'm not sure I will - but perhaps they can have the manufacturer deploy the corporation's keys in the roots of those hierarchies.

Also, the TPM's security as a trust anchor depends on its implementation. They look good in theory, but I have no idea if the various vendors actually implement them effectively.

[0] By far the best source I found is A Practical Guide to TPM 2.0 - Using the Trusted Platform Module in the New Age of Security by Arthur, Challener. It's also recommended by the Trusted Computing Group, the authors of TPM.