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Re: BUG in /bin/bash
From: strombrg () hydra acs uci edu (Dan Stromberg)
Date: Sat, 14 Sep 1996 13:33:14 -0700


This worked on all the unix variants I tried except debian linux, which
uses bash for sh instead of "the real sh".  I no longer have a copy of
ash to try.

I tried:

Solaris 2.4
Debian linux 1.1
Irix 5.2
OSF/1 3.2
SunOS 4.1.1
Ultrix 4.2

Sure sounds like this interpretation of ^ comes from upstream...

Roger Espel Llima wrote:

VULNERABILITY:  A variable declaration error in "bash" allows the character
                with value 255 decimal to be used as a command separator.

  That reminds me of a similar "little-known feature" on SunOS and
Solaris, where /bin/sh interprets '^' as a synonym for '|' :

$ sh -c 'echo blah ^ cat'
blah

  Again this could be exploited to fool CGI scripts (and ircII scripts
too) which execute shell commands with user-supplied data, after
checking for things like ';', '|' and '&'.

        -Roger
--
e-mail: roger.espel.llima () ens fr
WWW & PGP key: http://www.eleves.ens.fr:8080/home/espel/index.html



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