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                        SUSE Security Announcement

        Package:                ntp
        Announcement-ID:        SUSE-SA:2014:001
        Date:                   Monday, Jan 20 15:13:37 CET 2014
        Affected products:      all NTP server installations
        Vulnerability Type:     DDoS reflection attacks
        Severity (1-10):        7
        SUSE default package:   no
        Cross References:       CVE-2013-5211

    Content of this advisory:
        1) security vulnerability resolved:
             - DDoS reflection attacks in ntpd
           problem description
        2) solution/workaround
        3) special instructions and notes
        4) package location and checksums
        5) pending vulnerabilities, solutions, workarounds:
            - none
        6) standard appendix (further information)

______________________________________________________________________________

1) problem description, brief discussion

   The "monlist" command of the NTP protocol is currently abused in a DDoS
   reflection attack. This is done by spoofing packets from addresses to which
   the attack is directed to. The ntp installations itself are not target of
   the attack, but they are part of the DDoS network which the attacker is
   driving. It is therefore necessary to restrict ntp configurations to not
   answer spoofed "monlist" requests. It is not necessary to update the ntp
   software itself.

   Additional information can be found here:

      http://www.kb.cert.org/vuls/id/348126

   A more comprehensive description on how you can secure your
   infrastructure against NTP DDoS reflection attacks can be found here:

   http://www.team-cymru.org/ReadingRoom/Templates/secure-ntp-template.html

2) solution/workaround

   To ensure that your ntpd installation can not participate in a DDoS attack,
   add the following line to your configuration:

   restrict default noquery

3) special instructions and notes

   After applying the configuration changes, restart the ntp daemon.

4) package location and checksums

   not applicable

______________________________________________________________________________

5)  Pending vulnerabilities in SUSE Distributions and Workarounds:

    none

______________________________________________________________________________

6)  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 
       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 recommend against subscribing to security lists that cause the
       e-mail 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 
       to verify the signature of the package, where  is the
       file name 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 top-level 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-announce@suse.com
        -   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.

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