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Groups > gnu.bash.bug > #12019

Re: SHELLOPTS=xtrace security hardening

From Chet Ramey <chet.ramey@case.edu>
Newsgroups gnu.bash.bug
Subject Re: SHELLOPTS=xtrace security hardening
Date 2015-12-15 09:01 -0500
Message-ID <mailman.2151.1450188082.31583.bug-bash@gnu.org> (permalink)
References (1 earlier) <566DAFC6.4040407@case.edu> <20151213220817.GC7138@chaz.gmail.com> <20151214180113.169546iutu72yw9k@webmail.alunos.dcc.fc.up.pt> <20151214173231.GA6524@chaz.gmail.com> <20151215003016.598611ow5f3lw4qo@webmail.alunos.dcc.fc.up.pt>

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On 12/14/15 6:30 PM, up201407890@alunos.dcc.fc.up.pt wrote:
> Quoting "Stephane Chazelas" <stephane.chazelas@gmail.com>:
> 
> I understand what you're saying.
> As much as we would like, there's no way of stopping all attack vectors by
> only hardening bash, not only that, but also taking away its useful features.
> Though I still believe PS4 shouldn't be imported from the environment.

Maybe if running with uid 0.

>> Should we also block SHELLOPTS=history
>> HISTFILE=/some/file like /proc/$pid/fd/$fd and
>> TZ=/proc/$pid/fd/$fd (like for your /bin/date command) as that
>> allows DoS on other processes (like where those fds are for
>> pipes).
> 
> Mind explaining this one?
> I can't seem to write to HISTFILE in a non-interactive shell, or am i
> missing something?

You just need to enable history (set -o history).  History is independent
of whether or not the shell is interactive; it's just enabled by default
in interactive shells.

-- 
``The lyf so short, the craft so long to lerne.'' - Chaucer
		 ``Ars longa, vita brevis'' - Hippocrates
Chet Ramey, ITS, CWRU    chet@case.edu    http://cnswww.cns.cwru.edu/~chet/

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Re: SHELLOPTS=xtrace security hardening Chet Ramey <chet.ramey@case.edu> - 2015-12-15 09:01 -0500

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