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SuSE Linux Advisory: bind8

Nov 14, 2002, 14:22 (0 Talkback[s])

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                        SuSE Security Announcement

        Package:                bind8
        Announcement-ID:        SuSE-SA:2002:044
        Date:                   Wed Nov 13 17:00:00 CET 2002
        Affected products:      (7.0), 7.1, 7.2, 7.3, 8.0, 8.1,
                                SuSE Linux Database Server
                                SuSE eMail Server III, 3.1
                                SuSE Firewall
                                SuSE Linux Enterprise Server for S/390
                                SuSE Linux Connectivity Server
                                SuSE Linux Enterprise Server 7
                                SuSE Linux Office Server
        Vulnerability Type:     remote command execution
        Severity (1-10):        8
        SuSE default package:   yes
        Cross References:       CVE CAN-2002-1219,
                                CAN-2002-1220, CAN-2002-1221,

    Content of this advisory:
        1) security vulnerability resolved: Remote command execution
           in bind8 name server.
           problem description, discussion, solution and upgrade information
        2) pending vulnerabilities, solutions, workarounds: BIND4, reports
           of trojanized tcpdump/libpcap
        3) standard appendix (further information)


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

    The security research company ISS (Internet Security Services)
    has discovered several vulnerabilities in the BIND8 name server,
    including a remotely exploitable buffer overflow.

    Circumstancial evidence suggests that the Internet Software
    Consortium (maintainer of BIND) has been made aware of these issues
    in mid-October. Distributors of Open Source operating systems,
    including SuSE, were notified of these vulnerabilities via CERT
    approximately 12 hours before the release of the advisories by ISS
    and ISC on Tue, Nov 12. This notification did not include any details
    that allowed us to identify the vulnerable code, much less prepare
    a fix. Mails to ISC went unanswered for 36 hours.

    The SuSE security team regrets that the Internet Software Consortium
    has withheld vital information from the Internet community for so long,
    putting the majority of BIND users at risk. We would like to express
    our concern that the approach chosen by ISC and ISS is likely to
    erode trust in the security community if it becomes a model for dealing
    with security issues.

    We apologize to SuSE customers for not being able to provide timely
    fixes for this problem.

    The advisories by ISS and ISC mention the following problems
    in detail:

     1. There is a buffer overflow in the way named handles
        SIG records. This buffer overflow can be exploited to
        obtain access to the victim host under the account
        the named process is running with.

        In order to exploit this problem, the attacker must
        control an existing DNS domain, and must be allowed
        to perform a recursive query.

        The impact of this vulnerability is serious.

        In all SuSE products, named is configured to run as user "named"
        by default, so a potential attacker or virus/worm does not get
        immediate root access. However, this is merely an additional
        obstacle the attacker faces. It may be possible for the attacker
        to exploit other, unpatched local vulnerabilities such as the
        recently announced traceroute hole to obtain root privilege. It
        may also be possible for an attacker to obtain increased privilege
        by manipulating the DNS zones served by the victim BIND server.

        We recommend to upgrade to the provided packages. If this is
        not possible, we recommend to restrict recursive requests as a
        workaround. This can be done by adding a statement such as the
        following to /etc/named.conf:

        options {
                ... existing options ...

                # Restrict recursive queries to 192.168.1.*,
                # except
                # Order does matter.
                allow-recursion {

        Alternatively, you can add "recursion no;" to the options
        section to turn off recursion completely.

     2. There are several Denial Of Service problems in BIND8
        that allow remote attackers to terminate the name server

        At least one of these vulnerabilities seems to be exploitable
        even when the attacker is not allowed to perform recursive
        queries, so that the workaround suggested above is not
        effective against this bug.

    Both vulnerabilities are addressed by this update, using patches
    originating from ISC.

    Due to the severity of this issue, we will provide update packages
    for SuSE Linux 7.0, even though support for this product has officially
    been discontinued.

    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 packages using the command "rpm -Fhv file.rpm" to apply
    the update. After updating, make sure to restart the name server
    process by issuing the following command as root:

        rcnamed restart

    Our maintenance customers are being notified individually. The packages
    are being offered to install from the maintenance web.

    Intel i386 Platform:

    source rpm(s):

    source rpm(s):

    source rpm(s):

    source rpm(s):

    source rpm(s):

    source rpm(s):

    Sparc Platform:

    source rpm(s):

    AXP Alpha Platform:

    source rpm(s):

    source rpm(s):

    PPC Power PC Platform:

    source rpm(s):

    source rpm(s):

    source rpm(s):


2)  Pending vulnerabilities in SuSE Distributions and Workarounds:

        In addition to the vulnerabilities in BIND8 discussed above, ISS
        report several vulnerabilities in BIND4. As stated previously,
        SuSE has discontinued support for BIND4 and recommends that
        users upgrade to BIND8 as soon as possible.

    Trojaned libpcap/tcpdump
        There have been reports that the source packages of tcpdump and
        libpcap available from several FTP servers have been modified to
        include a trojan. We have checked our source packages for this
        and found them to be clean.


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, 
       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 un-installed rpm
       package file.
        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 "" upon installation or upgrade, provided that
           the package gpg is installed. The file containing the public key
           is placed at the top-level directory of the first CD (pubring.gpg)
           and at .

  - SuSE runs two security mailing lists to which any interested party may
        -   general/linux/SuSE security discussion. 
            All SuSE security announcements are sent to this list.
            To subscribe, send an email to 
        -   SuSE's announce-only mailing list.
            Only SuSE's security announcements are sent to this list.
            To subscribe, send an email to

    For general information or the frequently asked questions (faq) 
    send mail to:
        <> or
        <> respectively.

    SuSE's security contact is <> or <>.
    The <> 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 clear-text signature shows proof of the
    authenticity of the text.
    SuSE Linux AG 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 <>
pub  1024D/9C800ACA 2000-10-19 SuSE Package Signing Key <>