HPSBUX01164 SSRT4884 rev.4 - HP-UX TCP/IP Remote Denial of Service (DoS)

From: Security Alert (secure_at_hpchs.cup.hp.com)
Date: 07/19/05

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    SSRT4884 rev.4 - 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.

    10 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



         HP-UX B.11.22
         HP-UX B.11.00
         action: set ip_pmtu_strategy= 0 and either install binary
                 files or filter ICMP

         HP-UX B.11.11
         action: set ip_pmtu_strategy= 0 and install PHNE_33159

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

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

         HP-UX B.11.04
         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.


    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

    Workarounds are available for all three of these issues.

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

     ->Binary files are available for CAN-2004-0790 and CAN-2004-0791
    for HP-UX B.11.00 and B.11.22.

    Since PHNE_33159 is now available for B.11.11 the preliminary
    binary files for B.11.11 have been removed from the ftp site.

     ->Since PHNE_32606 is now available for B.11.23 the preliminary
    binary files for B.11.23 have been removed from the ftp site.

    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 binary files.

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

    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 <http://www.ietf.org/internet-drafts/
    draft-gont-tcpm-icmp-attacks-03.txt> has been implemented.
    Customers should consider whether this check reduces the risk of
    the exploit to the point that setting ip_pmtu_strategy=0 is not

    If the workaround for CAN-2004-1060 is to be used, please note
    the following:
    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
          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 command:

      /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.11.00 and B.11.22.
    Patches are available for 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.11.11 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*
      2844254744 2546 readme.11.00.txt
      2836317466 2469 readme.11.22.txt

       md5sum readme*
     d28504f8532192de6a4f33bba4ea90ec readme.11.00.txt
     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.

    For B.11.11 download and install PHNE_33159. The patch is
    available from < http://itrc.hp.com>.

     ->For B.11.23 download and install PHNE_32606. The patch is
    available from < http://itrc.hp.com>.

    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.

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    Version: PGP 8.1

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