Classic Computer Vulnerability Analysis Revisited

redtail writes "The original authors of the classic vulnerability analysis of Multics have revisited the lessons learned almost thirty years later. Their new paper, along with the original vulnerability analysis is published here by IBM. The original vulnerability analysis inspired the self-inserting compiler back door described by Ken Thompson in his Turing Award Lecture. "

Comments

Re:How little has changed

[Theodore Logan]

It's disappointing to see that a computer security paper written 30 years ago is still relevant today.

Indeed it is. However, if I recall correctly (the link is slashdotted, so I cannot check) the whole point of the paper is that this is a security "hole" (actually, it's not really a hole in itself, but more of a way to ascertain that a hole is not discovered) that cannot be closed. It describes a way of inserting a trojan into a program without it being visible in the source; the bottom line being that you can never trust code you didn't write directly for the machine, from scratch, yourself. And if this sort of bug was implemeted at hardware microcode level, you could not even trust writing directly for the machine.

That summary does not make the paper justice. Read it yourself when someone has posted a mirror. It's fascinating, simple, and absolutely brilliant.

Wrong.

[Animats]

Multics was one of the best operating systems ever in terms of reliablity and security. Go read the papers. People are still reusing basic ideas from Multics, like good CPU schedulers. Ease of use was mediocre, but then, this was ten years before DOS.

The big problem was that Multics was tied to a specific model of General Electric computer with custom security hardware. GE built some good early time-sharing systems in the 1960s, but sold off their computing business to Honeywell in the 1970s. Honeywell never marketed the Multics product line seriously, because it competed with other product lines that sold in bigger volume.