I’ve never found Wheeler’s approach very satisfying. It says “we can’t trust the compiler, so here’s a second compiler.” But I think it is too literal interpretation of Thompson’s attack and it is just moving goalposts not really stopping the essence of the attack. The viruses of the 1990s got so advanced they regularly intercepted the read calls and stripped their payload from inspection so hiding themselves, and you could imagine in the playpen where we think we trust some other external compiler we must also think we trust the read functions on the compromised machine etc. Thompson was thinking at a higher level than this.

I also think they’ve shortchanged the bootstrap build mitigation. They write:

    A utility such as strip sustains the attack whenever a tampered instance participates in the rebuild, even after the compiler seed shrinks to a few hundred bytes. 

Well, yes, if you presuppose your modified binary is used, then you will find that your attack continues, but that’s only because “P iff P” is a logical tautology. It would be true even when the seed shrinks to 0 bytes, or shrinks to a negative number of bytes, or shrinks into a miniature poodle and tap-dances across your keyboard.

The question that should have been addressed is “does the tampered instance participate in the build?”, and the whole point of these minimal-byte “seed” bootstraps is that they are just enough bytes of executable to do everything else from the source. So, no, the tampered instance won’t be participating in the build. We might even deploy our own tautology and say that if a pre-existing tainted binary participates in a build, then that build was not a bootstrap build, and therefore all bootstrap builds are in fact perfectly and definitionally immune to the attack.

Honestly, this whole paper kinda reads like an academic version of a slop CVE.

Works until AI compromises a bunch of OSes. And wouldn't there be difficulty comparing binaries built from significantly different environments? It sounds like some progress has been made in general for fixed identical builds, but isn't that also still a hard problem? I don't know enough low level C-level stuff about binary generation.