oss-sec mailing list archives
Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME
From: Chet Ramey <chet.ramey () case edu>
Date: Fri, 16 Sep 2016 14:49:11 -0400
On 9/16/16 1:38 PM, Jan Schaumann wrote:
John Haxby <john.haxby () oracle com> wrote:
(I didn't get this message.)
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.
This issue has been public since October, 2015 in Ubuntu's bug tracking system.
To clarify: this is only triggered if the hostname has been set, not the $HOSTNAME variable, right?
Bash doesn't use $HOSTNAME; it sets it if it's not already set. The shell's idea of the current hostname is set using gethostname(). If gethostname() fails, the hostname gets set to "??host??". The \h prompt expansion uses the shell's idea of the current hostname. If your privileged application (either a user with privilege or a hostname- setting agent) allows the hostname to be set to any arbitrary string of characters, you're going to have problems regardless. Chet -- ``The lyf so short, the craft so long to lerne.'' - Chaucer ``Ars longa, vita brevis'' - Hippocrates Chet Ramey, UTech, CWRU chet () case edu http://cnswww.cns.cwru.edu/~chet/
Current thread:
- CVE-2016-0634 -- bash prompt expanding $HOSTNAME John Haxby (Sep 16)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Jan Schaumann (Sep 16)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Chet Ramey (Sep 16)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME John Haxby (Sep 18)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Seth Arnold (Sep 19)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME John Haxby (Sep 20)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Chet Ramey (Sep 16)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Jan Schaumann (Sep 16)
- Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Chet Ramey (Sep 16)
- Re: Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Leo Famulari (Sep 27)
- Re: Re: CVE-2016-0634 -- bash prompt expanding $HOSTNAME Chet Ramey (Sep 29)