Date: Thu, 26 May 2005 11:08:50 -0600
From: "Boren, Rich (SSRT)" <rich.boren@...com>
To: <bugtraq@...urityfocus.com>
Subject: [security bulletin] SSRT4884 rev.0 - HP-UX TCP/IP Remote Denial of Service (DoS)



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HP SECURITY BULLETIN

HPSBUX01164     REVISION: 0

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

NOTICE:
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.

INITIAL RELEASE:
25 May 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 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.

BACKGROUND:

     AFFECTED VERSIONS

     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
     =============
     Networking.NET2-KRN
     action: install preliminary binary files

     IPSec.IPSEC2-KRN
     action: set ip_pmtu_strategy = 0

     HP-UX B.11.11
     =============
     Networking.NET2-KRN
     action: install preliminary binary files

     IPSec.IPSEC2-KRN
     action: set ip_pmtu_strategy = 0

     END AFFECTED VERSIONS

RESOLUTION:
As reported in NISCC VU#532967
http://www.uniras.gov.uk/niscc/docs/al-20050412-00308.html?lang=en
 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.

Workarounds
========

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:

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

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  (192.170.19.51)
     Login:     icmp
     Password:  icmp

    FTP Access: ftp://icmp:icmp@...c.external.hp.com/
            or: ftp://icmp:icmp@....170.19.51/


Download the appropriate readme file containing further
instructions:

   readme.11.11.txt
   readme.11.23.txt

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.


IPSec
====
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.


BULLETIN REVISION HISTORY:
Revision 0: 25 May 2005
  Initial release


HP-UX SPECIFIC SECURITY BULLETINS*:  Security Patch Check revision
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For more information:
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displayProductInfo.pl?productNumber=B6834AA


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* The Software Product Category that this Security Bulletin
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  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
accurate or complete for all user situations and, consequently, HP
will not be responsible for any damages resulting from user's use
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(c)Copyright 2005 Hewlett-Packard Development Company, L.P.
Hewlett-Packard Company shall not be liable for technical or
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provided is provided "as is" without warranty of any kind. To the
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