FreeBSD Security Advisory FreeBSD-SA-05:20.cvsbug [REVISED]

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

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    =============================================================================
    FreeBSD-SA-05:20.cvsbug Security Advisory
                                                              The FreeBSD Project

    Topic: Race condition in cvsbug

    Category: contrib
    Module: contrib_cvs
    Announced: 2005-09-07
    Credits: Marcus Meissner
    Affects: All FreeBSD releases
    Corrected: 2005-09-07 13:43:05 UTC (RELENG_6, 6.0-BETA5)
                    2005-09-07 13:43:23 UTC (RELENG_5, 5.4-STABLE)
                    2005-09-07 13:43:36 UTC (RELENG_5_4, 5.4-RELEASE-p7)
                    2005-09-09 19:26:19 UTC (RELENG_5_3, 5.3-RELEASE-p22)
                    2005-09-07 13:44:06 UTC (RELENG_4, 4.11-STABLE)
                    2005-09-07 13:44:20 UTC (RELENG_4_11, 4.11-RELEASE-p12)
                    2005-09-09 19:24:22 UTC (RELENG_4_10, 4.10-RELEASE-p18)
    CVE Name: CAN-2005-2693

    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 2005-07-07 Initial release.
    v1.1 2005-07-09 Additional related issues fixed in FreeBSD 4.10 and 5.3.

    I. Background

    cvsbug(1) is a utility for reporting problems in the CVS revision
    control system. It is based on the GNATS send-pr(1) utility.

    II. Problem Description

    A temporary file is created, used, deleted, and then re-created with
    the same name. This creates a window during which an attacker could
    replace the file with a link to another file. While cvsbug(1) is based
    on the send-pr(1) utility, this problem does not exist in the version
    of send-pr(1) distributed with FreeBSD.

    In FreeBSD 4.10 and 5.3, some additional problems exist concerning
    temporary file usage in both cvsbug(1) and send-pr(1).

    III. Impact

    A local attacker could cause data to be written to any file to which
    the user running cvsbug(1) (or send-pr(1) in FreeBSD 4.10 and 5.3) has
    write access. This may cause damage in itself (e.g., by destroying
    important system files or documents) or may be used to obtain elevated
    privileges.

    IV. Workaround

    Do not use the cvsbug(1) utility on any system with untrusted users.

    Do not use the send-pr(1) utility on a FreeBSD 4.10 or 5.3 system with
    untrusted users.

    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.

    [FreeBSD 4.10]
    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:20/cvsbug410.patch
    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:20/cvsbug410.patch.asc

    [FreeBSD 5.3]
    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:20/cvsbug53.patch
    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:20/cvsbug53.patch.asc

    [FreeBSD 4.11 and 5.4]
    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:20/cvsbug.patch
    # fetch ftp://ftp.FreeBSD.org/pub/FreeBSD/CERT/patches/SA-05:20/cvsbug.patch.asc

    b) Execute the following commands as root:

    # cd /usr/src
    # patch < /path/to/patch
    # cd /usr/src/gnu/usr.bin/cvs/cvsbug
    # make obj && make depend && make && make install
    # cd /usr/src/gnu/usr.bin/send-pr
    # 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/contrib/cvs/src/cvsbug.in 1.1.1.1.2.4
    RELENG_4_11
      src/UPDATING 1.73.2.91.2.13
      src/sys/conf/newvers.sh 1.44.2.39.2.16
      src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.3.2.1
    RELENG_4_10
      src/UPDATING 1.73.2.90.2.19
      src/sys/conf/newvers.sh 1.44.2.34.2.20
      src/contrib/cvs/src/cvsbug.in 1.1.1.1.2.2.6.2
      src/gnu/usr.bin/send-pr/send-pr.sh 1.13.2.13.2.1
    RELENG_5
      src/contrib/cvs/src/cvsbug.in 1.1.1.3.2.1
    RELENG_5_4
      src/UPDATING 1.342.2.24.2.16
      src/sys/conf/newvers.sh 1.62.2.18.2.12
      src/contrib/cvs/src/cvsbug.in 1.1.1.3.6.1
    RELENG_5_3
      src/UPDATING 1.342.2.13.2.25
      src/sys/conf/newvers.sh 1.62.2.15.2.27
      src/contrib/cvs/src/cvsbug.in 1.1.1.3.4.1
      src/gnu/usr.bin/send-pr/send-pr.sh 1.35.6.1
    RELENG_6
      src/contrib/cvs/src/cvsbug.in 1.1.1.3.8.1
    - -------------------------------------------------------------------------

    VII. References

    http://cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2005-2693

    The latest revision of this advisory is available at
    ftp://ftp.freebsd.org/pub/FreeBSD/CERT/advisories/FreeBSD-SA-05:20.cvsbug.asc
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