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Category:   Application (Generic)  >   texindex Vendors:   FreeBSD
FreeBSD texindex Unsafe Temporary Files May Let Local Users Gain Elevated Privileges
SecurityTracker Alert ID:  1015468
SecurityTracker URL:  http://securitytracker.com/id/1015468
CVE Reference:   CVE-2005-3011   (Links to External Site)
Date:  Jan 11 2006
Impact:   Modification of system information, Modification of user information, User access via local system
Fix Available:  Yes  Vendor Confirmed:  Yes  

Description:   A vulnerability was reported in texindex on FreeBSD. A local user may be able to obtain elevated privileges on the target system.

The texindex(1) utility uses temporary files in an unsafe manner. The sort_offline() function uses maketempname() which does not check to see if the filename already exists and also creates files with predictable file names. As a result, a local user can create a symbolic link (symlink) from a critical file on the system to a temporary file to be used by texindex. Then, when the target user runs texindex, the symlinked file may be overwritten with the privileges of the target user.

Impact:   A local user may be able to cause files to be modified with the privileges of the target user running texindex.
Solution:   FreeBSD has provided the following fix information [quoted]:

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE, 5-STABLE, or 6-STABLE,
or to the RELENG_6_0, RELENG_5_4, RELENG_5_3, RELENG_4_11, or
RELENG_4_10 security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.10,
4.11, 5.3, 5.4, and 6.0 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 4.x and 5.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex5x.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex5x.patch.asc

[FreeBSD 6.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/gnu/usr.bin/texinfo/libtxi
# make obj && make depend && make
# cd /usr/src/gnu/usr.bin/texinfo/texindex
# make obj && make depend && make && make install

The vendor's advisory is available at:

ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:01.texindex.asc

Vendor URL:  www.freebsd.org/security/ (Links to External Site)
Cause:   Access control error, State error
Underlying OS:  UNIX (FreeBSD)

Message History:   This archive entry has one or more follow-up message(s) listed below.
Nov 8 2006 (Red Hat Issues Fix) FreeBSD texindex Unsafe Temporary Files May Let Local Users Gain Elevated Privileges
Red Hat has released a fix for Red Hat Enterprise Linux 2.1, 3, and 4.
May 25 2007 (Apple Issues Fix) FreeBSD texindex Unsafe Temporary Files May Let Local Users Gain Elevated Privileges
Apple has released a fix for Mac OS X.



 Source Message Contents

Subject:  FreeBSD Security Advisory FreeBSD-SA-06:01.texindex [REVISED]

-----BEGIN PGP SIGNED MESSAGE-----
Hash: SHA1

=============================================================================
FreeBSD-SA-06:01.texindex                                   Security Advisory
                                                          The FreeBSD Project

Topic:          Texindex temporary file privilege escalation

Category:       contrib
Module:         texinfo
Announced:      2006-01-11
Credits:        Frank Lichtenheld
Affects:        All FreeBSD releases.
Corrected:      2006-01-11 08:02:16 UTC (RELENG_6, 6.0-STABLE)
                2006-01-11 08:03:18 UTC (RELENG_6_0, 6.0-RELEASE-p2)
                2006-01-11 08:03:55 UTC (RELENG_5, 5.4-STABLE)
                2006-01-11 08:04:33 UTC (RELENG_5_4, 5.4-RELEASE-p9)
                2006-01-11 08:05:54 UTC (RELENG_5_3, 5.3-RELEASE-p24)
                2006-01-11 08:06:47 UTC (RELENG_4, 4.11-STABLE)
                2006-01-11 08:07:18 UTC (RELENG_4_11, 4.11-RELEASE-p14)
                2006-01-11 08:08:08 UTC (RELENG_4_10, 4.10-RELEASE-p20)
CVE Name:       CAN-2005-3011

For general information regarding FreeBSD Security Advisories,
including descriptions of the fields above, security branches, and the
following sections, please visit
<URL:http://www.freebsd.org/security/>.

0.   Revision History.

v1.0 2006-01-11  Initial release.
v1.1 2006-01-11  Corrected instructions for rebuilding texindex.

I.   Background

TeX is a document typesetting system which is popular in the mathematics,
physics, and computer science realms because of its ability to typeset
complex mathematical formulas.  texindex(1) is a utility which is often
used to generate a sorted index of a TeX file.

II.  Problem Description

The "sort_offline" function used by texindex(1) employs the "maketempname"
function, which produces predictable file names and fails to validate that
the paths do not exist.

III. Impact

These predictable temporary file names are problematic because they
allow an attacker to take advantage of a race condition in order to
execute a symlink attack, which could enable them to overwrite files
on the system in the context of the user running the texindex(1) utility.

IV.  Workaround

No workaround is available, but the problematic code is only executed
if the input file being processed is 500kB or more in length; as a
result, users working with documents of less than several hundred pages
are very unlikely to be affected.

V.   Solution

Perform one of the following:

1) Upgrade your vulnerable system to 4-STABLE, 5-STABLE, or 6-STABLE,
or to the RELENG_6_0, RELENG_5_4, RELENG_5_3, RELENG_4_11, or
RELENG_4_10 security branch dated after the correction date.

2) To patch your present system:

The following patches have been verified to apply to FreeBSD 4.10,
4.11, 5.3, 5.4, and 6.0 systems.

a) Download the relevant patch from the location below, and verify the
detached PGP signature using your PGP utility.

[FreeBSD 4.x and 5.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex5x.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex5x.patch.asc

[FreeBSD 6.x]
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex.patch
# fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-06:01/texindex.patch.asc

b) Execute the following commands as root:

# cd /usr/src
# patch < /path/to/patch
# cd /usr/src/gnu/usr.bin/texinfo/libtxi
# make obj && make depend && make
# cd /usr/src/gnu/usr.bin/texinfo/texindex
# make obj && make depend && make && make install

VI.  Correction details

The following list contains the revision numbers of each file that was
corrected in FreeBSD.

Branch                                                           Revision
  Path
- -------------------------------------------------------------------------
RELENG_4
  contrib/texinfo/util/texindex.c                             1.1.1.3.2.4
RELENG_4_11
  src/UPDATING                                             1.73.2.91.2.15
  src/sys/conf/newvers.sh                                  1.44.2.39.2.18
  contrib/texinfo/util/texindex.c                         1.1.1.3.2.3.6.1
RELENG_4_10
  src/UPDATING                                             1.73.2.90.2.21
  src/sys/conf/newvers.sh                                  1.44.2.34.2.22
  contrib/texinfo/util/texindex.c                         1.1.1.3.2.3.4.1
RELENG_5
  contrib/texinfo/util/texindex.c                             1.1.1.7.4.1
RELENG_5_4
  src/UPDATING                                            1.342.2.24.2.18
  src/sys/conf/newvers.sh                                  1.62.2.18.2.14
  contrib/texinfo/util/texindex.c                             1.1.1.7.8.1
RELENG_5_3
  src/UPDATING                                            1.342.2.13.2.27
  src/sys/conf/newvers.sh                                  1.62.2.15.2.29
  contrib/texinfo/util/texindex.c                             1.1.1.7.6.1
RELENG_6
  contrib/texinfo/util/texindex.c                             1.1.1.8.2.1
RELENG_6_0
  src/UPDATING                                              1.416.2.3.2.7
  src/sys/conf/newvers.sh                                    1.69.2.8.2.3
  contrib/texinfo/util/texindex.c                             1.1.1.8.4.1
- -------------------------------------------------------------------------

VII. References

http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-3011

The latest revision of this advisory is available at
ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-06:01.texindex.asc
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