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SuSE Security Announcement: libz/zlib

Mar 12, 2002, 01:11 (0 Talkback[s])

____________________________________________________________________________

                        SuSE Security Announcement

        Package:                libz/zlib
        Announcement-ID:        SuSE-SA:2002:010
        Date:                   Monday, Mar 11th 2002 20:45 MET
        Affected products:      6.4, 7.0, 7.1, 7.2, 7.3
                                SuSE Linux Database Server
                                SuSE eMail Server III
                                SuSE Firewall
                                SuSE Linux Connectivity Server
                                SuSE Linux Enterprise Server 7
        Vulnerability Type:     remote command execution
        Severity (1-10):        8
        SuSE default package:   yes
        Other affected systems: systems with recent versions of the
                                compression library

    Content of this advisory:
        1) security vulnerability resolved: libz/zlib
           problem description, discussion, solution and upgrade information
        2) pending vulnerabilities, solutions, workarounds
        3) standard appendix (further information)

____________________________________________________________________________

1)  problem description, brief discussion, solution, upgrade information

    The zlib compression library is being used by many applications to
    provide data compression/decompression routines. An error in a
    decompression routine can corrupt the internal data structures of
    malloc by a double call to the free() function. If the data processed
    by the compression library is provided from an untrusted source, it
    may be possible for an attacker to interfere with the process using the
    zlib routines. The attack scenario includes a denial of service attack
    and memory/data disclosure, but it may also be possible to insert
    arbitrary code into the running program and to execute this code.
    This update fixes the known problems in the libz/zlib as a permanent
    fix. There exists no temporary workaround that can efficiently remedy
    the problem.

    It is expected that a large range of software is affected. The systems
    affected are by no means limited to Linux systems or other open-source
    based operating systems.

    Note:
    The libz compression library is being used by several hundred packages
    in all SuSE products. While the update of the libz package as itself is
    not problematic, it must be noted that many packages bring their own
    compression library in their source code. If these packages link against
    their own version of the libz compression library, their source needs
    to be fixed as well. Considering the length of a combined Security
    Announcement, SuSE Security publish a tandem-announcement, consisting
    of two seperate Security Announcements released in quick succession:

        SuSE-SA:2002:010    libz/zlib
        SuSE-SA:2002:011    packages containing libz/zlib


    Acknowledgements:
    We thank Owen Taylor who tracked down the bug in the compression
    library, and to Matthias Clasen for reporting the problem that seemed
    to be located in the libpng at first.
    We also thank Mark Adler and Jean-loup Gailly, the authors of the zlib
    package, for their quick response in the double-free() matter.



    SPECIAL INSTALL INSTRUCTIONS:
    ===============================

    * Installation of the update package:
    The installation of shared libraries on an actively running system
    should be done with special care. During the update of the libz package,
    runtime-linking the shared libraries is likely to fail for processes
    that execute a new binary with the execve(2) system call. If at all
    applicable, a system receiving the update should be kept as quiet as
    possible during the time that the RPM command runs. In doubt, please
    perform the update in Single User Mode ("init S"). The RPM command must
    not be interrupted during its operation.
    After performing the update, the processes that still use the old
    version of the package must be restarted for the libz upgrade to
    become effective. If you have performed the update in Single User Mode,
    this has been done already, and you can safely return to your default
    runlevel. If in doubt, reboot your system to make sure that the changes
    are becoming effective.



    Please download the update package for your distribution and verify its
    integrity by the methods listed in section 3) of this announcement.
    Then, install the package using the command "rpm -Fhv file.rpm" to apply
    the update.
    Our maintenance customers are being notified individually. The packages
    are being offered to install from the maintenance web.


    i386 Intel Platform:

    SuSE-7.3
    ftp://ftp.suse.com/pub/suse/i386/update/7.3/a1/libz-1.1.3-597.i386.rpm
799491ca29f9bf95e3e38a73f25abea8
    source rpm:
    ftp://ftp.suse.com/pub/suse/i386/update/7.3/zq1/libz-1.1.3-597.src.rpm
a4071506da6ab39dca5495530028d291

    SuSE-7.2
    ftp://ftp.suse.com/pub/suse/i386/update/7.2/a1/libz-1.1.3-573.i386.rpm
2197aff65b09fb05b8969ace64d7a4a6
    source rpm:
    ftp://ftp.suse.com/pub/suse/i386/update/7.2/zq1/libz-1.1.3-573.src.rpm
1694ed149ca946e7ea1cc2da3f14c181

    SuSE-7.1
    ftp://ftp.suse.com/pub/suse/i386/update/7.1/a1/libz-1.1.3-570.i386.rpm
c309b104231c596bb81008c38a4e473c
    source rpm:
    ftp://ftp.suse.com/pub/suse/i386/update/7.1/zq1/libz-1.1.3-570.src.rpm
950c86970cd7c3fc0a30cfab176769ac

    SuSE-7.0
    ftp://ftp.suse.com/pub/suse/i386/update/7.0/a1/libz-1.1.3-571.i386.rpm
8bde6b53a78e5f920080bfa3b6a236a6
    source rpm:
    ftp://ftp.suse.com/pub/suse/i386/update/7.0/zq1/libz-1.1.3-571.src.rpm
718c36c91cd0f97466cbb2303967d51c

    SuSE-6.4
    ftp://ftp.suse.com/pub/suse/i386/update/6.4/a1/libz-1.1.3-575.i386.rpm
270fc89c1be6854288925a9326f9ca6e
    source rpm:
    ftp://ftp.suse.com/pub/suse/i386/update/6.4/zq1/libz-1.1.3-575.src.rpm
625ed87653f820f7f65a4a8e045f6cc2




    Sparc Platform:

    SuSE-7.3
    ftp://ftp.suse.com/pub/suse/sparc/update/7.3/a1/libz-1.1.3-419.sparc.rpm
f890b6d04e9164fc2afa05241c0e94c9
    source rpm:
    ftp://ftp.suse.com/pub/suse/sparc/update/7.3/zq1/libz-1.1.3-419.src.rpm
818d39946dc6c73f425620fba546935c

    SuSE-7.1
    ftp://ftp.suse.com/pub/suse/sparc/update/7.1/a1/libz-1.1.3-406.sparc.rpm
ff4ea0da2c5126311f654b2896a70dd9
    source rpm:
    ftp://ftp.suse.com/pub/suse/sparc/update/7.1/zq1/libz-1.1.3-406.src.rpm
c3a49ea61f2642d53e29c8a81e07bfd9

    SuSE-7.0
    ftp://ftp.suse.com/pub/suse/sparc/update/7.0/a1/libz-1.1.3-406.sparc.rpm
b9e22f0ff9785ca1d226bd2c5e135909
    source rpm:
    ftp://ftp.suse.com/pub/suse/sparc/update/7.0/zq1/libz-1.1.3-406.src.rpm
25c2b7cd4e20da69b7d806551966bae8





    AXP Alpha Platform:

    SuSE-7.1
    ftp://ftp.suse.com/pub/suse/axp/update/7.1/a1/libz-1.1.3-434.alpha.rpm
e8cd8561a1434c36afcccd856d79a483
    source rpm:
    ftp://ftp.suse.com/pub/suse/axp/update/7.1/zq1/libz-1.1.3-434.src.rpm
f7c21774f76fb240205291c4e91ad83c

    SuSE-7.0
    ftp://ftp.suse.com/pub/suse/axp/update/7.0/a1/libz-1.1.3-434.alpha.rpm
15510fc7563e669145d28a69e0e77d8e
    source rpm:
    ftp://ftp.suse.com/pub/suse/axp/update/7.0/zq1/libz-1.1.3-434.src.rpm
008bc8f743e64e26dccd89baf882b214

    SuSE-6.4
    ftp://ftp.suse.com/pub/suse/axp/update/6.4/a1/libz-1.1.3-435.alpha.rpm
7d29b7d929e4b36dd6268058bf3c7538
    source rpm:
    ftp://ftp.suse.com/pub/suse/axp/update/6.4/zq1/libz-1.1.3-435.src.rpm
67a4bd496c7625aaa3049417930e97f8




    PPC Power PC Platform:

    SuSE-7.3
    ftp://ftp.suse.com/pub/suse/ppc/update/7.3/a1/libz-1.1.3-432.ppc.rpm
b06097a1496ca5fd7b3492c2ab4f7337
    source rpm:
    ftp://ftp.suse.com/pub/suse/ppc/update/7.3/zq1/libz-1.1.3-432.src.rpm
45127ca06e4b019b2e700a0c87c2edb6

    SuSE-7.1
    ftp://ftp.suse.com/pub/suse/ppc/update/7.1/a1/libz-1.1.3-417.ppc.rpm
783a39b17295e169d344a5f7f1ad7e86
    source rpm:
    ftp://ftp.suse.com/pub/suse/ppc/update/7.1/zq1/libz-1.1.3-417.src.rpm
2ac1e404e8a6723b1eb101b7c7d118e8

    SuSE-7.0
    ftp://ftp.suse.com/pub/suse/ppc/update/7.0/a1/libz-1.1.3-417.ppc.rpm
24901e0c7ccb6bf5bf17b2af60596d96
    source rpm:
    ftp://ftp.suse.com/pub/suse/ppc/update/7.0/zq1/libz-1.1.3-417.src.rpm
f9e6cda577a5007baa84fb9940ec718d

    SuSE-6.4
    ftp://ftp.suse.com/pub/suse/ppc/update/6.4/a1/libz-1.1.3-416.ppc.rpm
b3580d5e1b3702c330957bde4422486c
    source rpm:
    ftp://ftp.suse.com/pub/suse/ppc/update/6.4/zq1/libz-1.1.3-416.src.rpm
32cbca2dbc911da128b5bd1d19789792



____________________________________________________________________________

2)  Pending vulnerabilities in SuSE Distributions and Workarounds:

  - Please see the following SuSE Security Announcement SuSE-SA:2002:011
    (packages containing libz) for upgrade information regarding packages
    that bring their own compression library in their source.


____________________________________________________________________________

3)  standard appendix: authenticity verification, additional information

  - Package authenticity verification:

    SuSE update packages are available on many mirror ftp servers all over
    the world. While this service is being considered valuable and important
    to the free and open source software community, many users wish to be
    sure about the origin of the package and its content before installing
    the package. There are two verification methods that can be used
    independently from each other to prove the authenticity of a downloaded
    file or rpm package:
    1) md5sums as provided in the (cryptographically signed) announcement.
    2) using the internal gpg signatures of the rpm package.

    1) execute the command
        md5sum <name-of-the-file.rpm>
after you downloaded the file from a SuSE ftp server or its mirrors.
       Then, compare the resulting md5sum with the one that is listed in the
       announcement. Since the announcement containing the checksums is
       cryptographically signed (usually using the key security@suse.de),
       the checksums show proof of the authenticity of the package.
       We disrecommend to subscribe to security lists which cause the
       email message containing the announcement to be modified so that
       the signature does not match after transport through the mailing
       list software.
       Downsides: You must be able to verify the authenticity of the
       announcement in the first place. If RPM packages are being rebuilt
       and a new version of a package is published on the ftp server, all
       md5 sums for the files are useless.

    2) rpm package signatures provide an easy way to verify the authenticity
       of an rpm package. Use the command
        rpm -v --checksig <file.rpm>
to verify the signature of the package, where <file.rpm> is the
       filename of the rpm package that you have downloaded. Of course,
       package authenticity verification can only target an uninstalled rpm
       package file.
       Prerequisites:
        a) gpg is installed
        b) The package is signed using a certain key. The public part of this
           key must be installed by the gpg program in the directory
           ~/.gnupg/ under the user's home directory who performs the
           signature verification (usually root). You can import the key
           that is used by SuSE in rpm packages for SuSE Linux by saving
           this announcement to a file ("announcement.txt") and
           running the command (do "su -" to be root):
            gpg --batch; gpg < announcement.txt | gpg --import
           SuSE Linux distributions version 7.1 and thereafter install the
           key "build@suse.de" upon installation or upgrade, provided that
           the package gpg is installed. The file containing the public key
           is placed at the toplevel directory of the first CD (pubring.gpg)
           and at ftp://ftp.suse.com/pub/suse/pubring.gpg-build.suse.de .


  - SuSE runs two security mailing lists to which any interested party may
    subscribe:

    suse-security@suse.com
        -   general/linux/SuSE security discussion.
            All SuSE security announcements are sent to this list.
            To subscribe, send an email to
                <suse-security-subscribe@suse.com>.

    suse-security-announce@suse.com
        -   SuSE's announce-only mailing list.
            Only SuSE's security annoucements are sent to this list.
            To subscribe, send an email to
                <suse-security-announce-subscribe@suse.com>.

    For general information or the frequently asked questions (faq)
    send mail to:
        <suse-security-info@suse.com> or
        <suse-security-faq@suse.com> respectively.

    =====================================================================
    SuSE's security contact is <security@suse.com> or <security@suse.de>.
    The <security@suse.de> public key is listed below.
    =====================================================================
____________________________________________________________________________

    The information in this advisory may be distributed or reproduced,
    provided that the advisory is not modified in any way. In particular,
    it is desired that the cleartext signature shows proof of the
    authenticity of the text.
    SuSE GmbH makes no warranties of any kind whatsoever with respect
    to the information contained in this security advisory.

Type Bits/KeyID    Date       User ID
pub  2048R/3D25D3D9 1999-03-06 SuSE Security Team <security@suse.de>
pub  1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <build@suse.de>

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Roman Drahtmüller,
SuSE Security.
- --
 -                                                                      -
| Roman Drahtmüller      <draht@suse.de> // "You don't need eyes to see, |
  SuSE GmbH - Security           Phone: //             you need vision!"
| Nürnberg, Germany     +49-911-740530 //           Maxi Jazz, Faithless |
 -                                                                      -

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