[security bulletin] SSRT4884 rev.0 - HP-UX TCP/IP Remote Denial of Service (DoS)

From: Boren, Rich (SSRT) (rich.boren_at_hp.com)
Date: 05/26/05

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    Date: Thu, 26 May 2005 11:08:50 -0600
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    SSRT4884 rev.0 - 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.

    25 May 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 532967, CAN-2004-0790, CAN-2004-0791

    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.11.22
         HP-UX B.11.04
         HP-UX B.11.00
         action: set ip_pmtu_strategy = 0, block certain ICMP messages

         HP-UX B.11.23
         action: install preliminary binary files

         action: set ip_pmtu_strategy = 0

         HP-UX B.11.11
         action: install preliminary binary files

         action: set ip_pmtu_strategy = 0


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

    Preliminary binary files are available for B.11.11 and B.11.23.
    Instructions for downloading and installing the binary files are
    given below.


    Until patches are available the issue may be worked around by
    filtering out certain ICMP messages and by ignoring the
    "Fragmentation Needed and DF Bit Set" ICMP message.

    The following ICMP messages could be filtered via filtering
    technology such as firewalls or host based filters:

      Protocol Unreachable
      Port Unreachable
      Source Quench

    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.

    In addition the "Fragmentation Needed and DF Bit Set" ICMP message
    can be ignored by setting ip_pmtu_strategy = 0 as follows:

    Note: HPSBUX01137 recommends setting ip_pmtu_strategy = 0 or 3 as
    a workaround. The current issue has a different root cause and
    cannot be worked around with ip_pmtu_strategy = 3.

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


    This value will take effect when the system is rebooted.
    Until the system can be rebooted the ip_pmtu_strategy value for
    new connections can be set with the ndd(1M) command:

      /usr/bin/ndd -set /dev/ip ip_pmtu_strategy 0

    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.11.11 and B.11.23.
    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: ftp://icmp:icmp@hprc.external.hp.com/
                or: ftp://icmp:icmp@

    Download the appropriate readme file containing further


    Verify the cksum or md5sum:

       cksum readme*
      4156903999 3555 readme.11.11.txt
      2827648934 3676 readme.11.23.txt

       md5sum readme*
      3926e5970fe50872cfa2f1998355f25c readme.11.11.txt
      41d45bcc312dee4ef297a4438e37b81c readme.11.23.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.

    Customers using the IPSec product may install the binary files for
    B.11.11 and B.11.23 as mentioned above. However, that will not
    resolve all the issues for IPSec. Until a binary file is
    available for the IPSec product it will be necessary to use the
    ip_pmtu_strategy = 0 workaround as discussed above.

    In summary:
    B.11.11,B.11.23 -- install binary files
    B.11.11,B.11.23 plus IPSec -- install binary files and
                                  set ip_pmtu_strategy = 0

    MANUAL ACTIONS: Yes - NonUpdate

    For B.11.00, B.11.04, and B.11.22:
    Set ip_pmtu_strategy=0 and filter out the following ICMP messages:

      Protocol Unreachable
      Port Unreachable
      Source Quench

    For B.11.11 and B.11.23:
    Apply the workaround above or install binary files.

    For B.11.11 and B.11.23 IPSec:
    In addition to installing binary files, set ip_pmtu_strategy=0.

    Revision 0: 25 May 2005
      Initial release

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    * The Software Product Category that this Security Bulletin
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      Bulletin number:
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    (c)Copyright 2005 Hewlett-Packard Development Company, L.P.
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    Version: PGP 8.1

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

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