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SubjectRe: Unexecutable Stack / Buffer Overflow Exploits...
On Wed, 29 Dec 1999, Horst von Brand wrote:
> > And even for example, if you run bind non-root, if they can
> > clobber your name server files and screw up name service, even that will
> > suffice to raise major havoc. Besides if they can get a shell as ANY UID
> > that gives them an inside base from which to advance their attack.
> No such attack has been posted recently...

I'm sorry I don't remember where, bugtrack I think, but a buffer overflow
exploit for BIND was just recently posted which just recently necessitated yet
another upgrade, and I know quite a few people that got nailed by it.

If you set it up to run non-root; it would still be possible to get a
shell under that UID and clobber files that BIND manipulates; not to mention
that it would give you an inside position from which to launch further attacks.

> There are audit projects around, the software _is_ getting fixed, server
> stuff is being designed/programmed more carefully these days. Sure, you
> could decree that all servers must be written in Java or some other "safe"
> language, but that will just shift the problems to the implementation of
> the language, and have a huge cost in rewriting and retesting. Plus cost a
> bundle in performance...

I've been doing this for decades not years, and constantly the software
_is_ getting fixed; but it never arrives at that state. Why? Because
protocols, features, etc evolve, people are always adding new functionality,
new bugs are created as fast if not faster than old ones are destroyed.

> Where do you think script kiddies get their exploit scripts from? They
> don't write them themselves: The real crackers share them with the
> community. Just like the hacker community shares patches and cool
> programs. So you can keep out 99.99% only until one of the 0.01% finds out
> a way around it. The danger of "nonexecutable stack" is that it creates a
> sense of security, which might be justified as long as it is rare. Once it
> becomes widespread, it will be useless in short time, and _everybody_ will
> have to pay the cost for nothing at all, while feeling smugly secure.

One could make the same argument for a root password. It's another layer,
one more thing to have to get around. Absolute security doesn't exist.

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