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Message-ID: <20110727112613.7645881f@redhat.com>
Date: Wed, 27 Jul 2011 11:26:13 +0200
From: Tomas Hoger <thoger@...hat.com>
To: oss-security@...ts.openwall.com
Subject: Re: CVE request - dhcp clients

On Wed, 27 Jul 2011 10:57:39 +0200 Sebastian Krahmer wrote:

> Can you point us to the exact version and location in code where
> the vulnerability is?

I've not previously looked at the code more closely to find the exact
spot to be fixed.  However, I have successfully reproduced the issue
with busybox 1.15.1 at least, not sure if I looked at any older
version too.  It should be trivial to reproduce by running udhcpc -s
<script>, where script just dumps whole env.  You should see
server-provided options exported (hostname, domain).

> I remember to have checked udhcpc at that time and neither I found it
> setting a hostname or parsing the options for a hostname.

Looks like fill_envp is the place:
http://git.busybox.net/busybox/tree/networking/udhcp/dhcpc.c#n341

The logic was little different in older versions:
http://git.busybox.net/busybox/tree/networking/udhcp/dhcpc.c?id=9ac5596a#n336

When I talked to upstream, they did see the issue and opened the bug:
https://bugs.busybox.net/show_bug.cgi?id=3979

-- 
Tomas Hoger / Red Hat Security Response Team

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