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

Isn't publishing vulnerabilities illegal?

[Anonymous Coward]

I thought the point of the DMCA was to let technology move faster by encouraging companies to leave their systems unsecure and making it illegal to discuss and exploit the vulnerabilities instead.

Er, uh, not exactly

[baldass_newbie]

With the growth of individual workstations and personal computers, developers concluded (incorrectly) that security was not as important on minicomputers or single-user computers. As the Internet grew, it became clear that even single-user computers needed security, but those ill-founded decisions continue to haunt us today.

Big shock. AC does not read article. Weakly attempts a troll.

Re:Self-inserting compiler.

[The Raven]

Skepticism is irrelevant... it *did* work. I believe it simply checked the name of the output file... if it was creating an output target called 'gcc' (or the equivalent, whatever it had back then) then it compiled in the hack. I do not know how robust it was, but from what I remember reading, it worked, so it was obviously robust enough.

Re:I see an opportunity for IBM

[Zeinfeld]

Plan 9 [bell-labs.com] from Bell Labs.

Plan-9 was not designed from the ground up and certainly not for security. Plan-9 had some features beyond the UNIX core but it was certainly not a clean sheet of paper job. The first version even came out with the typesetter and games programs that were long since obsolete under UNIX.

The only O/S that I know of to be designed 'from the ground up' since VM-UNIX came out is Windows NT. UNIX was started before VMS but did not leave the research lab until after VMS launched. OS-X is simply a merger of NeXTStep and Mac-OS.

Windows NT the operating system is designed from the ground up to meet the Orange book B2 security requirements. That statement means less than it might when you find out what B2 means, i.e. almost nothing relevant to the real world. A B2 O/S cannot be connected to any sort of network and remain B2 secure, still interested?

The point is that design of the O/S is irrelevant unless the applications are also designed to be secure. There have been remarkably few security compromises of either UNIX or Windows NT, almost all the bug reports are in the layered applications. Take Outlook off Windows and Sendmail off Unix and the stats look oh so much better. Ten years ago I had a flame war with Eric Altman which later made it to the UNIX Hater's list, basically he said that he had finaly got a grip on the bugs and I pointed out that he still had no process and no clue when it came to security. Guess what, he still hasn't.

There are plenty of good replacements for sendmail that do not introduce arbitrary Turing complete languages for arbitrary purposes. Unfortunately the UNIX world simply won't use them.

There is a company working on a secure O/S, it requires secure hardware and is codenamed Palladium. You still want more security?

Stacks

[Spazmania]

Third, stacks on the Multics processors grew in the positive direction, rather than the negative direction. This meant that if you actually accomplished a buffer overflow, you would be overwriting unused stack frames rather than your own return pointer, making exploitation much more difficult.

How hard would this be to integrate this into GNU C and Linux? As I understand it, growing the heap from the bottom and growing the stack from the top with the yet unused space in the middle is just a matter of convention. How much trouble would it be to reverse the two so that the heap grows from the top and the stack from the bottom?

Seems like it ought to be a simple patch to the most vexing class of security problems we all experience.