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Countering the trusting trust attackCountering the trusting trust attackPosted Feb 5, 2010 21:42 UTC (Fri) by paulj (subscriber, #341)In reply to: Countering the trusting trust attack by Baylink Parent article: Security in the 20-teens
Thompson implementing his attack as a compiler attack is a detail, primarily
because source code was the normal form of software interchange but the basic compiler toolchain obviously still required passing around binaries. In short it was the *only* place he could have implemented an attack by subverting binaries. His paper is explicit that the compiler attack is merely a demonstration of a more fundamental problem of having to place trust in computer systems. Particularly, he mentions microcode as a possible level of attack - clearly a completely different thing from compiler level and indication that Thompson was making a very general point.
To think that Thompson's attack is only about compilers is surely to miss the
Also, I don't expect clairvoyance. Indeed, you miss my point about which
I think perhaps I should properly write up my criticism...
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Countering the trusting trust attack Posted Feb 5, 2010 21:52 UTC (Fri) by Baylink (subscriber, #755) [Link]
Because I am a believer in the traditions of science, yes, I think it would be an excellent idea if you wrote up formally your problems with his paper...
which I *promise* I'm going to read, tonight while I wait for a server upgrade to finish. :-)
And certainly any level of the stack can be attacked, and I understand that was his point. But one either has to say "there's no practical way for me to validate the microcode of the CPU, and thus there's a practical limite to what I can verify", or one has to -- in fact -- do that validation.
If one can.
As we note on RISKS regularly, there are two issues at hand here: "pick your own low-hanging fruit", ie: make sure you apply extra security balm equally to all layers of your problem (as adjusted by your threat estimates at each layer), and "know your CBA": the amount of security at all levels you apply has to be in keeping with not only your threat estimate, but with what the bad guys can *get*.
This is, in particular, the part of the issue that terrorists throw monkey wrenches into: trying to inspire asymmetrical responses to what are, objectively, low-level threats. Your opponent wears himself out on the cape and never sees the sword. Bruce Schneier likes to address this issue.
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