Re: OT? Are chroots immune to buffer overflows?

From: jove@gaza.halo.nu
Date: 05/22/02


Date: Wed, 22 May 2002 09:21:15 -0500 (CDT)
From: <jove@gaza.halo.nu>
To: Andreas Ferber <aferber@techfak.uni-bielefeld.de>

There has also been shellcode which will listen on a port, and accept data
which it will then execute as shell code thus nullifying the need to have
more buffer space then what is neccessary to execve /bin/sh.

Cheers,
-Jove

On Wed, 22 May 2002, Andreas Ferber wrote:

> On Wed, May 22, 2002 at 03:48:16PM +1200, Jason Haar wrote:
> >
> > Most buffer overflows I've seen attempt to infiltrate the system enough to
> > run /bin/sh. In chroot'ed environments, /bin/sh doesn't (shouldn't!) exist -
> > so they fail.
> >
> > Is it as simple as that? As 99.999% of the system binaries aren't available
> > in the jail, can a buffer overflow ever work?
>
> The buffer overflow still works as expected (the bug is in the daemon,
> not in /bin/sh), though the shellcode used in most precooked exploits
> doesn't work. If the buffer is large enough so that the attacker can
> place more code than just an exec("/bin/sh") into it, he can still do
> all nasty things inside the bounds of the jail (e.g. uploading his own
> shell and executing that one ;-)
>
> Andreas
> --
> Andreas Ferber - dev/consulting GmbH - Bielefeld, FRG
> ---------------------------------------------------------
> +49 521 1365800 - af@devcon.net - www.devcon.net
>