SSRT4884 rev.6 - HP-UX TCP/IP Remote Denial of Service (DoS)

From: Security Alert (secure_at_hpchs.cup.hp.com)
Date: 08/16/05

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    HP SECURITY BULLETIN

    HPSBUX01164 REVISION: 6

    SSRT4884 rev.6 - HP-UX TCP/IP Remote Denial of Service (DoS)

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

    INITIAL RELEASE:
    15 August 2005

    POTENTIAL SECURITY IMPACT:
    Remote Denial of Service (DoS)

    SOURCE:
    Hewlett-Packard Company
    HP Software Security Response Team

    VULNERABILITY SUMMARY:
    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).

    REFERENCES:
    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
    Release).

    BACKGROUND:

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

    <http://www.uniras.gov.uk/niscc/docs/
    al-20050412-00308.html?lang=en>

    There are three issues reported in NISCC VU#532967:

     CVE number: CAN-2004-0790
     <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0790>
      CVE number: CAN-2004-0791
     <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-0791>
      CVE number: CAN-2004-1060
     <http://www.cve.mitre.org/cgi-bin/cvename.cgi?name=CAN-2004-1060>

         AFFECTED VERSIONS

         HP-UX B.11.00
         =============
         Networking.NET2-KRN
         action: install PHNE_33395, optionally set ip_pmtu_strategy=0

         HP-UX B.11.04
         =============
         Networking.NET2-KRN
       ->action: install PHNE_33427, optionally set ip_pmtu_strategy=0

         HP-UX B.11.11
         =============
         Networking.NET2-KRN
         action: install PHNE_33159, optionally set ip_pmtu_strategy=0

         HP-UX B.11.22
         =============
         Networking.NET2-KRN
       action: install binary files, optionally set ip_pmtu_strategy=0

         HP-UX B.11.23
         =============
         Networking.NET2-KRN
         action: install PHNE_32606, optionally set ip_pmtu_strategy=0

         HP-UX B.11.11
         HP-UX B.11.23
         =============
         TOUR_PRODUCT.T-NET2-KRN
         action: set ip_pmtu_strategy= 0 and filter ICMP

         END AFFECTED VERSIONS

     ->Note: The latest TOUR (Transport Optional Upgrade Release)
     -> functionality is available as follows:

      -> B.11.11 TOUR version 2.4 upgrade
      -> B.11.23 contained in the
      -> HP-UX 11i v2 September 2004 release

     ->Customers who wish to continue using an earlier version of TOUR
     ->on B.11.23 should apply the workaround (set ip_pmtu_strategy= 0
      ->and filter ICMP).

     ->Customers who are able to update to the latest TOUR
     ->functionality in B.11.23 should 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.

    RESOLUTION:

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

               For B.11.00 - PHNE_33395 or subsequent
     -> For B.11.04 - PHNE_33427 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."

    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:

     B.11.11
        1. Use the workarounds.
           or
        2. Remove TOUR and install the patch.

     B.11.23
        1. Use the workarounds.
            or
        2. Upgrade to the HP-UX 11i v2 September 2004 release
            and install the patch.

    TOUR(Transport Optional Upgrade Release) is available from
    <http://www.hp.com/go/softwaredepot>.

    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:
    <http://www.gont.com.ar/drafts/icmp-attacks-against-tcp.html>.
    Customers should consider whether this check reduces the risk of
    the exploit to the point that setting ip_pmtu_strategy=0 is not
    required.

     Note: ip_pmtu_strategy=0 sets the PMTU to 576 bytes and
     -> clears the "Don't Fragment" bit. This disables
     -> PMTU discovery.
           For IPv4 the Next-Hop MTU may be as low as 68 bytes.
           Therefore setting ip_pmtu_strategy=0 may cause
      -> performance to decrease.

    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
    AN-2004-1060 ip_pmtu_strategy=0 must be used.

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

    Workarounds:

      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)

      CAN-2004-1060

         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:

    TRANSPORT_NAME[n]=ip
    NDD_NAME[n]=ip_pmtu_strategy
    NDD_VALUE[n]=0

    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
    parameters:

      /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.11.22. 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 (192.170.19.51)
         Login: icmp
         Password: icmp

        FTP Access:
                     ftp://icmp:icmp@hprc.external.hp.com/
                or: ftp://icmp:icmp@192.170.19.51/
        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
    instructions:

       readme.11.22.txt

    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)

       OR

        b. Install the appropriate binary file or patch.

    BULLETIN REVISION HISTORY:
    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.

    Revision 6: 15 August 2005
      PHNE_33427 is available for B.11.04.
      Clarified the B.11.23 TOUR information.
      Modified ip_pmtu_strategy note.

    HP-UX SPECIFIC SECURITY BULLETINS*: Security Patch Check revision
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    For more information:
    http://www.software.hp.com/cgi-bin/swdepot_parser.cgi/cgi/
    displayProductInfo.pl?productNumber=B6834AA

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    "HP is broadly distributing this Security Bulletin in order to
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    --
    Yours truly,
    HP S/W Security Team
    WTEC Cupertino, California
    Return-Path: secure@cup.hp.com
    Reply-to: security-alert@hp.com
    

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