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FreeBSD-SA-02:01                                            Security Advisory
                                                                FreeBSD, Inc.

Topic:          Directory permission vulnerability in pkg_add [REVISED]

Category:       core
Module:         pkg_install
Announced:      2002-01-04
Revised:        2002-01-07
Credits:        The Anarcat <anarcat@anarcat.dyndns.org>
Affects:        All versions of FreeBSD prior to the correction date.
Corrected:      2001/11/22 17:40:36 UTC (4.4-STABLE aka RELENG_4)
                2001/12/07 20:58:46 UTC (4.4-RELEASEp1 aka RELENG_4_4)
                2001/12/07 20:57:19 UTC (4.3-RELEASEp21 aka RELENG_4_3)
FreeBSD only:   NO

0.   Revision History

v1.0  2002-01-04  Initial release
v1.1  2002-01-07  Correct terminology in problem description.

I.   Background

pkg_add is a utility program used to install software package
distributions on FreeBSD systems.

II.  Problem Description

pkg_add extracts the contents of the package to a temporary directory,
then moves files from the temporary directory to their ultimate
destination on the system.  The temporary directory used in the
extraction was created with world-searchable permissions, allowing
arbitrary users to examine the contents of the package as it was
being extracted.  This might allow users to attack world-writable
parts of the package during installation.

III. Impact

A local attacker may be able to modify the package contents and
potentially elevate privileges or otherwise compromise the system.
There are no known exploits as of the date of this advisory.

IV.  Workaround

1) Remove or discontinue use of the pkg_add binary until it has
been upgraded.

2) When running pkg_add, create a secure temporary directory (such
as /var/tmp/inst) and secure the directory permissions (chmod 700
/var/tmp/inst).  Set the TMPDIR environment variable to this
directory before running pkg_add.

V.   Solution

1) Upgrade your vulnerable FreeBSD system to 4.4-STABLE, or the
RELENG_4_4 or RELENG_4_3 security branches dated after the respective
correction dates.

2) FreeBSD 4.x systems prior to the correction date:

The following patch has been verified to apply to FreeBSD 4.3-RELEASE,
4.4-RELEASE, and 4-STABLE dated prior to the correction date.  This
patch may or may not apply to older, unsupported releases of FreeBSD.

Download the patch and the detached PGP signature from the following
locations, and verify the signature using your PGP utility.

ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:01/pkg_add.patch
ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-02:01/pkg_add.patch.asc

Execute the following commands as root:

# cd /usr/src
# patch -p < /path/to/patch
# cd /usr/src/usr.sbin/pkg_install
# make depend && make all install

VI.  Correction details

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

Path                                                             Revision
  Branch
- -------------------------------------------------------------------------
src/usr.sbin/pkg_install/lib/pen.c
  HEAD                                                               1.37
  RELENG_4                                                       1.31.2.6
  RELENG_4_4                                                 1.31.2.2.2.1
  RELENG_4_3                                                 1.31.2.1.2.1
- -------------------------------------------------------------------------

VII. References

<URL:http://www.FreeBSD.org/cgi/query-pr.cgi?pr=32172>
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