Re: Unexecutable Stack / Buffer Overflow Exploits...

Horst von Brand (vonbrand@pincoya.inf.utfsm.cl)
Thu, 30 Dec 1999 12:03:16 -0300


"Homme R. Bitter" <homme@vuurwerk.nl> said:
> On Wed, 29 Dec 1999, Horst von Brand wrote:
> > And note that the latest round of attacks against Solaris bind (I never run
> > stock distribution servers as a policy matter, they usually lag _way_
> > behind in security) gave me a _huge_ /var/adm/messages, full of messages
> > from bind that was being bombarded with many thousands of weird requests.
> > Installing nonexecutable stack would have given me a whole bunch of nice
> > core files, and a nameserver that did not work for more than a couple of
> > seconds at a time. That isn't exactly "security" in my book.

> Solaris != linux

But the problem would stay exactly the same with an outdated (or just not
updated) Linux distribution.

> The openwall/Solar Designer patch works with bind.

I didn't say it doesn't. Just that I prefer to get a bind that is immune to
this kind of attacks than cores all over the place and a bind that doesn't
work because it is being probed from all over the planet.

> Try it out on a non production box and see if you can break it, then start
> comparing those results with an unmodified linux kernel.

Linus stated it _won't_ go into the kernel, because it just papers over
bugs in userland code, and buys very little (if any) extra security, and
moreover breaks legitimate programs. He outlined ways to use stack
overflows even in this case, and to think crackers won't be able to use
them just because they are harder to get right (note that those attacks
will also work on unpatched systems) is delusion. Dangerous one.

-- 
Dr. Horst H. von Brand                       mailto:vonbrand@inf.utfsm.cl
Departamento de Informatica                     Fono: +56 32 654431
Universidad Tecnica Federico Santa Maria              +56 32 654239
Casilla 110-V, Valparaiso, Chile                Fax:  +56 32 797513

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