FreeBSD Security Advisory FreeBSD-SA-05:11.gzip

From: FreeBSD Security Advisories (security-advisories_at_freebsd.org)
Date: 06/09/05

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    Date: Thu, 9 Jun 2005 10:30:19 GMT
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    =============================================================================
    FreeBSD-SA-05:11.gzip Security Advisory
                                                              The FreeBSD Project

    Topic: gzip directory traversal and permission race vulnerabilities

    Category: contrib
    Module: gzip
    Announced: 2005-06-09
    Credits: Ulf Harnhammar, Imran Ghory
    Affects: All FreeBSD releases
    Corrected: 2005-06-08 21:26:27 UTC (RELENG_5, 5.4-STABLE)
                    2005-06-08 21:27:44 UTC (RELENG_5_4, 5.4-RELEASE-p2)
                    2005-06-08 21:29:15 UTC (RELENG_5_3, 5.3-RELEASE-p16)
                    2005-06-08 21:29:53 UTC (RELENG_4, 4.11-STABLE)
                    2005-06-08 21:30:43 UTC (RELENG_4_11, 4.11-RELEASE-p10)
                    2005-06-08 21:31:16 UTC (RELENG_4_10, 4.10-RELEASE-p15)
    CVE Name: CAN-2005-0988, CAN-2005-1228

    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/>.

    I. Background

    gzip is a file compression utility.

    II. Problem Description

    Two problems related to extraction of files exist in gzip:

    The first problem is that gzip does not properly sanitize filenames
    containing "/" when uncompressing files using the -N command line
    option.

    The second problem is that gzip does not set permissions on newly
    extracted files until after the file has been created and the file
    descriptor has been closed.

    III. Impact

    The first problem can allow an attacker to overwrite arbitrary local
    files when uncompressing a file using the -N command line option.

    The second problem can allow a local attacker to change the
    permissions of arbitrary local files, on the same partition as the one
    the user is uncompressing a file on, by removing the file the user is
    uncompressing and replacing it with a hardlink before the uncompress
    operation is finished.

    IV. Workaround

    Do not use the -N command line option on untrusted files and do not
    uncompress files in directories where untrusted users have write
    access.

    V. Solution

    Perform one of the following:

    1) Upgrade your vulnerable system to 4-STABLE or 5-STABLE, or to the
    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, and 5.4 systems.

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

    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:11/gzip.patch
    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:11/gzip.patch.asc

    b) Execute the following commands as root:

    # cd /usr/src
    # patch < /path/to/patch
    # cd /usr/src/gnu/usr.bin/gzip
    # 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
      src/gnu/usr.bin/gzip/gzip.c 1.10.2.1
    RELENG_4_11
      src/UPDATING 1.73.2.91.2.11
      src/sys/conf/newvers.sh 1.44.2.39.2.14
      src/gnu/usr.bin/gzip/gzip.c 1.10.26.1
    RELENG_4_10
      src/UPDATING 1.73.2.90.2.16
      src/sys/conf/newvers.sh 1.44.2.34.2.17
      src/gnu/usr.bin/gzip/gzip.c 1.10.24.1
    RELENG_5
      src/gnu/usr.bin/gzip/gzip.c 1.11.2.1
    RELENG_5_4
      src/UPDATING 1.342.2.24.2.11
      src/sys/conf/newvers.sh 1.62.2.18.2.7
      src/gnu/usr.bin/gzip/gzip.c 1.11.6.1
    RELENG_5_3
      src/UPDATING 1.342.2.13.2.19
      src/sys/conf/newvers.sh 1.62.2.15.2.21
      src/gnu/usr.bin/gzip/gzip.c 1.11.4.1
    - -------------------------------------------------------------------------

    VII. References

    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-0988
    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-1228
    http://marc.theaimsgroup.com/?l=bugtraq&m=111271860708210
    http://marc.theaimsgroup.com/?l=bugtraq&m=111402732406477

    The latest revision of this advisory is available at
    ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:11.gzip.asc
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