[security bulletin] SSRT4884 rev.5 - HP-UX TCP/IP Remote Denial of Service (DoS)

Date: 07/25/05

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    SSRT4884 rev.5 - HP-UX TCP/IP Remote Denial of Service (DoS)

    There are no restrictions for distribution of this Security
    Bulletin provided that it remains complete and intact.

    The information in this Security Bulletin should be acted upon
    as soon as possible.

    24 July 2005

    Remote Denial of Service (DoS)

    Hewlett-Packard Company
    HP Software Security Response Team

    A potential security vulnerability has been identified with HP-UX
    running TCP/IP. This vulnerability could be remotely exploited by
    an unauthorized user to cause a Denial of Service(DoS).

    NISCC VU#532967, CAN-2004-0790, CAN-2004-0791, CAN-2004-1060

    SUPPORTED SOFTWARE VERSIONS*: ONLY impacted versions are listed.
    HP-UX B.11.00, B.11.04, B.11.11, B.11.22, B.11.23 running TCP/IP.
    HP-UX B.11.11 and B.11.23 running TOUR (Transport Optional Upgrade


    As reported in NISCC VU#532967 ICMP messages may be used to attack
    TCP/IP connections.


    There are three issues reported in NISCC VU#532967:

     CVE number: CAN-2004-0790
      CVE number: CAN-2004-0791
      CVE number: CAN-2004-1060


         HP-UX B.11.00
       ->action: install PHNE_33395, optionally set ip_pmtu_strategy=0

         HP-UX B.11.04
         action: set ip_pmtu_strategy=0 and filter ICMP

         HP-UX B.11.11
       ->action: install PHNE_33159, optionally set ip_pmtu_strategy=0

         HP-UX B.11.22
     ->action: install binary files, optionally set ip_pmtu_strategy=0

         HP-UX B.11.23
      ->action: install PHNE_32606, optionally set ip_pmtu_strategy=0

         HP-UX B.11.11
         HP-UX B.11.23
         action: set ip_pmtu_strategy=0 and filter ICMP


     Note: The latest TOUR (Transport Optional Upgrade Release),
           version 2.4, is available on B.11.11 only. The latest
           Transport Functionality is available to B.11.23 customers
           in the HP-UX 11i v2 September 2004 release. Customers
           using TOUR on B.11.23 can apply the workaround (set
           ip_pmtu_strategy= 0 and filter ICMP) or upgrade to the
           HP-UX 11i v2 September 2004 release. After upgrading the
           action for B.11.23 Networking.NET2-KRN listed above should
           be implemented.

     ->Patches are available for the core network product
     ->from <http://itrc.hp.com>:

     -> For B.11.00 - PHNE_33395 or subsequent
     -> For B.11.11 - PHNE_33159 or subsequent
     -> For B.11.23 - PHNE_32606 or subsequent

     ->Binary files are available for B.11.22 (details are below).

     ->Optionally set ip_pmtu_strategy=0. Please see the discussion
     ->below, "Workaround for CAN-2004-1060 may not be necessary."

    Until binary files are available for B.11.04 the workarounds below
    should be used.

    Note: If the TOUR (Transport Optional Upgrade Release) product is
          installed the binary files cannot be used.

    Until the TOUR product is revised there are several options:

        1. Use the workarounds.
     ->2. Remove TOUR and install the patch.

        1. Use the workarounds.
        2. Upgrade to the HP-UX 11i v2 September 2004 release
     -> and install the patch.

    TOUR(Transport Optional Upgrade Release) is available from

    Workaround for CAN-2004-1060 may not be necessary.
    Although changes in the binary files and patches for CAN-2004-0790
    and CAN-2004-0791 do not prevent the exploit of CAN-2004-1060,
    they do make it less likely to succeed. The sequence number check
    suggested in section 5.1 of 'ICMP attacks against TCP' has been
    implemented. The Internet Draft of 'ICMP attacks against TCP'
    can be found here:
    Customers should consider whether this check reduces the risk of
    the exploit to the point that setting ip_pmtu_strategy=0 is not

     ->Note: ip_pmtu_strategy=0 sets the PMTU to 576 bytes.
     -> For IPv4 the Next-Hop MTU may be as low as 68 bytes.
     -> Therefore setting ip_pmtu_strategy=0 may cause
     -> connections to stall.

    If the workaround for CAN-2004-1060 is to be used, please note the
    HPSBUX01137 recommends setting ip_pmtu_strategy = 0 or 3 as a
    workaround for the problem of CAN-2005-1192. CAN-2004-1060 has a
    different root cause and cannot be worked around with
    p_pmtu_strategy=3. To work around both CAN-2005-1192 and
    CAN-2004-1060 ip_pmtu_strategy=0 must be used.

    Please refer to the Manual Actions section below for a summary of
    the required actions.


      CAN-2004-0790 and CAN-2004-0791

         Filter out the following ICMP messages:

        Type 3, Code 2 (Destination Unreachable, Protocol Unreachable)
        Type 3, Code 3 (Destination Unreachable, Port Unreachable)
        Type 4, Code 0 (Source Quench)


         Set ip_pmtu_strategy=0.

    Note: Filtering "Protocol Unreachable" and "Port Unreachable"
          should not be done without careful testing. Filtering these
          out may interfere with the correct functioning of network
          components. Filtering "Source Quench" should present
          little risk.

    Setting ip_pmtu_strategy=0
    Edit /etc/rc.config.d/nddconf to add the following:


    where 'n' is the next available index value as described in the
    nddconf comments.

    This value will take effect when the system is rebooted.
    Until the system can be rebooted use the following command
    to read the /etc/rc.config.d/nddconf file and set the tunable

      /usr/bin/ndd -c

    The ip_pmtu_strategy parameter can be displayed by the following

      /usr/bin/ndd -get /dev/ip ip_pmtu_strategy

    Note: Since open connections will remain potentially vulnerable
          until they are closed and certain internal data structures
          are released it is recommended that the system be rebooted.

    Note: There is a defect that will cause "ndd -c" to fail if there
          are more than 10 directives in /etc/rc.config.d/nddconf.
          That defect is fixed in the following patches:

                  B.11.11 - PHNE_25644 or subsequent
                  B.11.04 - PHNE_26076 or subsequent
                  B.11.00 - PHNE_26125 or subsequent

    Preliminary binary files

     ->Preliminary binary files are available for B.11.22. Patches
    are available for B.11.00, B.11.11 and B.11.23. The patches and
    the preliminary binary files address CAN-2004-0790 and
    CAN-2004-0791 only. Although changes in the patches and binary
    files for CAN-2004-0790 and CAN-2004-0791 do not prevent the
    exploit of CAN-2004-1060, they do make it less likely to succeed.

    Instructions for downloading and installing the binary files are
    contained in readme files available here:

         System: hprc.external.hp.com (
         Login: icmp
         Password: icmp

        FTP Access:
                or: ftp://icmp:icmp@

        Note: The links above may not work for all browsers. If the
              link fails the url should be entered directly into the
              browser's address field.

     ->Since a patch is available for B.11.00 the readme.11.00.txt and
    corresponding binary files have been removed from the ftp site.

    Since a patch is available for B.11.11 the readme.11.11.txt and
    corresponding binary files have been removed from the ftp site.

    Since a patch is available for B.11.23 the readme.11.23.txt and
    corresponding binary files have been removed from the ftp site.

    Download the appropriate readme file containing further


    Verify the cksum or md5sum:

    Note: The readme files have not changed since rev.1 of this
          Security Bulletin.

       cksum readme*
      2836317466 2469 readme.11.22.txt

       md5sum readme*
     cafbb24f3dc7131501142f75deaeccbd readme.11.22.txt

    Download and install the binary files as discussed in the readme
    files. The binary files are available in the same directory as
    the readme files.

    MANUAL ACTIONS: Yes - NonUpdate
    1. Set ip_pmtu_strategy=0

    2. EITHER
        a. Filter out the following ICMP messages:

        Type 3, Code 2 (Destination Unreachable, Protocol Unreachable)
        Type 3, Code 3 (Destination Unreachable, Port Unreachable)
        Type 4, Code 0 (Source Quench)


        b. Install the appropriate binary file or patch (binary file
            not available for B.11.04).

    Revision 0: 25 May 2005
      Initial release

    Revision 1: 1 June 2005
      Binary files for B.11.00 and B.11.22 are available.
      Added information about CAN-2004-1060.
      The "set ip_pmtu_strategy=0" workaround is required even if
      binary files are installed.
      Removed IPSec information.

    Revision 2: 19 June 2005
      TOUR (Transport Optional Upgrade Release) on B.11.11 and B.11.23
      is potentially vulnerable.
      Added a description of the sequence number check implemented in
      the binary files.

    Revision 3: 27 June 2005
      PHNE_33159 is available for B.11.11. The B.11.11 binary files
      have been removed from the ftp site.

    Revision 4: 10 July 2005
      PHNE_32606 is available for B.11.23. The B.11.23 binary files
      have been removed from the ftp site.

    Revision 5: 24 July 2005
      PHNE_33395 is available for B.11.00. The B.11.00 binary files
      have been removed from the ftp site.
      Added discussion of ip_pmtu_strategy=0. It is optional if
      patches are installed.
      Moved or deleted some text for readability.

    HP-UX SPECIFIC SECURITY BULLETINS*: Security Patch Check revision
    B.02.00 analyzes all HP-issued Security Bulletins to provide a
    subset of recommended actions that potentially affect a specific
    HP-UX system.

    For more information:

    SUPPORT: For further information, contact normal HP Services
    support channel.

    REPORT: To report a potential security vulnerability with any HP
    supported product, send Email to: security-alert@hp.com. It is
    strongly recommended that security related information being
    communicated to HP be encrypted using PGP, especially exploit
    information. To obtain the security-alert PGP key please send an
    e-mail message to security-alert@hp.com with the Subject of
    'get key' (no quotes).

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    Security Bulletins via Email:


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    To review previously published Security Bulletins visit:

    * The Software Product Category that this Security Bulletin
      relates to is represented by the 5th and 6th characters of the
      Bulletin number:
        GN = HP General SW,
        MA = HP Management Agents,
        MI = Misc. 3rd party SW,
        MP = HP MPE/iX,
        NS = HP NonStop Servers,
        OV = HP OpenVMS,
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        TL = HP Trusted Linux,
        TU = HP Tru64 UNIX,
        UX = HP-UX,
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    System management and security procedures must be reviewed
    frequently to maintain system integrity. HP is continually
    reviewing and enhancing the security features of software products
    to provide customers with current secure solutions.

    "HP is broadly distributing this Security Bulletin in order to
    bring to the attention of users of the affected HP products the
    important security information contained in this Bulletin. HP
    recommends that all users determine the applicability of this
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    action. HP does not warrant that this information is necessarily
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    will not be responsible for any damages resulting from user's use
    or disregard of the information provided in this Bulletin. To the
    extent permitted by law, HP disclaims all warranties, either
    express or implied, including the warranties of merchantability
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    (c)Copyright 2005 Hewlett-Packard Development Company, L.P.
    Hewlett-Packard Company shall not be liable for technical or
    editorial errors or omissions contained herein. The information
    provided is provided "as is" without warranty of any kind. To the
    extent permitted by law, neither HP nor its affiliates,
    subcontractors or suppliers will be liable for incidental, special
    or consequential damages including downtime cost; lost profits;
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    The information in this document is subject to change without
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    Company in the United States and other countries. Other product
    and company names mentioned herein may be trademarks of their
    respective owners.

    Version: PGP 8.1

    -----END PGP SIGNATURE-----

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