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Date: Fri, 26 Sep 2014 18:06:45 +0100
From: Gennady Kupava <gennady.kupava@...il.com>
To: oss-security@...ts.openwall.com
Subject: Fwd: CVE-2014-6271: remote code execution through bash
The way how bash exports functions is really scary:
1. You can set both variable and export function with same name.
$ f () { a; }
$ export -f f
$ export f=3
$ echo $f
3
$ ksh
$ cat /proc/$$/environ|xargs -0 -n1|grep -w f
f=3
f=() { a
$ echo $f
3
SUS says storing two environment varianles with same name is undefined
behavour:
http://pubs.opengroup.org/onlinepubs/7908799/xbd/envvar.html
2. Bash partially hides environment variable holding function:
$ f () { a; }
$ export -f f
$ echo $f
[ nothing ]
Both things above look like good grounds for hackers.
Gennady
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