full-disclosure - Re: The GNU C library dynamic linker expands $ORIGIN in setuid library search path

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Date: Tue, 19 Oct 2010 21:52:54 +0200
From: Tavis Ormandy <taviso@...xchg8b.com>
To: full-disclosure@...ts.grok.org.uk
Subject: Re: The GNU C library dynamic linker expands
	$ORIGIN in setuid library search path

Hanno Böck <hanno@...eck.de> wrote:

> Am Monday 18 October 2010 schrieb Tavis Ormandy:
> > # Open a file descriptor to the target binary (note: some users are
> > surprised # to learn exec can be used to manipulate the redirections of
> > the current # shell if a command is not specified. This is what is
> > happening below). $ exec 3< /tmp/exploit/target
> 
> I tried to reproduce this on Gentoo and it fails at this point. It seems
> the reason is that suid-binaries are not world-readable on Gentoo (on
> Debian they are) - this seems to be a useful security measure.
> 

Hi Hanno, I explained why this is insufficient in the Notes section of my
advisory, along with some example code to circumvent this.

Tavis.

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