Re: Program-invoking Symbolic Links?

From: viro
Date: Thu Aug 05 2004 - 13:01:34 EST


On Thu, Aug 05, 2004 at 07:34:42PM +0200, Måns Rullgård wrote:
> > ~luser/foo => "cp /bin/sh /tmp/...; chmod 4777 /tmp/...; cat ~luser/foo.real"
> >
> > Any questions?
>
> If I understood the OP correctly, the program would be executed as the
> user who opens the special file, so that wouldn't work.

Yes, it would. Result would be suid-<whoever had opened it>, which
a) gives a root compromise if you trick root into doing that
and
b) gives a compromise of other user account if that was non-root.

Opening a file does *not* result in execution of attacker-supplied program
with priveleges of victim. Breaking that warranty opens a fsck-knows-how-many
holes.
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