full-disclosure - shtool insecure temporary file creation

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Message-ID: <775D1D90-25B0-4BA2-84F6-6B86D703B5D1@zataz.net>
Date: Wed May 25 18:54:52 2005
From: exploits at zataz.net (ZATAZ.net)
Subject: shtool insecure temporary file creation

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#########################################################

shtool insecure temporary file creation

Vendor: http://www.gnu.org/software/shtool/
Advisory: http://www.zataz.net/adviso/shtool-05252005.txt
Vendor informed: no more vendor
Exploit available: yes
Impact : low
Exploitation : low

#########################################################

shtool contain a security flaw wich could allow a
malicious local user to create or overwrite content off arbitrary files
with the right off the user how use shtool.

The vulnerability is a race condition.

A lot off products use shtool, for exemple :

- - ocan-mysql
- - SellaNMS
- - ipcmp
- - OOPSE
- - OpenLDAP
- - PHP
- - OpenPKG
- - others ....

##########
Versions:
##########

shtool <= 2.0.1

##########
Solution:
##########

As I know only Gentoo has provide an update to shtool.
Use mktemp, umask and chmod to create secure temporary file

#########
Timeline:
#########

Discovered : 2005-05-25
Vendor notified : 2005-05-25
Vendor response : no more vendor
Vendor fix :  no vendor fix
Disclosure :  2005-05-25

#####################
Technical details :
#####################

Vulnerable code :
- -----------------

572 #   establish a temporary file on request
573 if [ ".$gen_tmpfile" = .yes ]; then
574     if [ ".$TMPDIR" != . ]; then
575         tmpdir="$TMPDIR"
576     elif [ ".$TEMPDIR" != . ]; then
577         tmpdir="$TEMPDIR"
578     else
579         tmpdir="/tmp"
580     fi
581     tmpfile="$tmpdir/.shtool.$$"
582     rm -f $tmpfile >/dev/null 2>&1
583     touch $tmpfile
584     chmod 600 $tmpfile
585 fi

597 #   cleanup procedure
598 shtool_exit () {
599     rc="$1"
600     if [ ".$gen_tmpfile" = .yes ]; then
601         rm -f $tmpfile >/dev/null 2>&1 || true
602     fi
603     exit $rc
604 }

The gen_tmpfile is used for tarball, subst, scpp ant path actions.

#########
Related :
#########

Bug report : http://bugs.gentoo.org/show_bug.cgi?id=93782

#####################
Credits :
#####################

Eric Romang (eromang@...az.net - ZATAZ Audit)
Thxs to Gentoo Security Team. (Taviso, jaervosz, solar, etc.)
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