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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