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             AUSCERT External Security Bulletin Redistribution

             ESB-2005.0644 -- HP Security Bulletin HPSBUX01164
       SSRT4884 rev.6 - HP-UX TCP/IP Remote Denial of Service (DoS)
                              18 August 2005


        AusCERT Security Bulletin Summary

Product:           TCP/IP
Publisher:         Hewlett-Packard
Operating System:  HP-UX B.11.23 and prior
Impact:            Denial of Service
Access:            Remote/Unauthenticated
CVE Names:         CAN-2005-1192 CAN-2004-1060 CAN-2004-0791

Ref:               ESB-2005.0575

Original Bulletin: http://h20293.www2.hp.com/cgi-bin/swdepot_parser.cgi/cgi/displayProductInfo.pl?productNumber=B6834AA

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Hash: SHA1



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

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

15 August 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: install PHNE_33427, optionally set ip_pmtu_strategy=0

     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)
 -> 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.


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:

    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 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.


  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

  /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

    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.

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
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
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information. To obtain the security-alert PGP key please send an
e-mail message to security-alert@hp.com with the Subject of
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  relates to is represented by the 5th and 6th characters of the
  Bulletin number:
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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
information to their individual situations and take appropriate
action. HP does not warrant that this information is necessarily
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or disregard of the information provided in this Bulletin. To the
extent permitted by law, HP disclaims all warranties, either
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and fitness for a particular purpose, title and non-infringement."

(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;
damages relating to the procurement of substitute products or
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The information in this document is subject to change without
notice. Hewlett-Packard Company and the names of Hewlett-Packard
products referenced herein are trademarks of Hewlett-Packard
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


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