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Date: Fri, 16 Sep 2016 15:46:51 -0400
From: Chet Ramey <chet.ramey@...e.edu>
To: John Haxby <john.haxby@...cle.com>, oss-security@...ts.openwall.com
Cc: chet.ramey@...e.edu
Subject: Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME
On 9/16/16 12:16 PM, John Haxby wrote:
> Hello All,
>
> A little while ago, one of our users discovered that by setting the
> hostname to $(something unpleasant), bash would run "something
> unpleasant" when it expanded \h in the prompt string.
I finally got this message, three hours later.
I assume you're using $HOSTNAME as a shorthand; bash only uses the
return value from gethostname().
It's unlikely that something like this could be accomplished without
existing privilege. If you have a fake DHCP server on your network, for
instance, you have massive problems aside from this issue. If someone
sets the hostname on the local machine, he already has privilege.
>
> I believe the fix in parse.y is this (Chet, please correct me if I'm wrong):
Yes, that is the current fix for this. There are other ways to do it.
This issue has been public since October, 2015, in Ubuntu's bash bug
database.
https://bugs.launchpad.net/ubuntu/+source/bash/+bug/1507025
--
``The lyf so short, the craft so long to lerne.'' - Chaucer
``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, UTech, CWRU chet@...e.edu http://cnswww.cns.cwru.edu/~chet/
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