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SSRT4884 rev.2 - 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.

19 June 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, 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.11.23
HP-UX B.11.22
HP-UX B.11.11
HP-UX B.11.00
action: set ip_pmtu_strategy= 0 and either install binary
files or filter ICMP

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#53296:

CVE number: CAN-2004-0790

CVE number: CAN-2004-0791

CVE number: CAN-2004-1060

Workarounds are available for all three of these issues.

Binary files are available for CAN-2004-0790 and CAN-2004-0791 for
HP-UX B.11.00, B.11.11, B.11.22, and B.11.23.

->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.
-> or
-> 2. Remove TOUR and install the binary files.

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

->TOUR(Transport Optional Upgrade Release) is available from

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

Only a workaround is available for CAN-2004-1060.
However, although changes in the 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.
->The sequence number check suggested in section 5.1 of
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 required.

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 components.
Filtering "Source Quench" should present little risk.

Note: 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
ip_pmtu_strategy=3. Only setting ip_pmtu_strategy=0 will work
around both CAN-2005-1192 and CAN-2004-1060.

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.11.00, B.11.11,
B.11.22, and B.11.23. These preliminary binary files address
CAN-2004-0790 and CAN-2004-0791 only. It will still be necessary
to work around CAN-2004-1060. However, although changes in the
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

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:

->Note: The readme files have not changed since rev.1 of this
Security Bulletin.

cksum readme*
28442547442546 readme.11.00.txt
21349385553525 readme.11.11.txt
28363174662469 readme.11.22.txt
4951652883646 readme.11.23.txt

md5sum readme*
d28504f8532192de6a4f33bba4ea90ec readme.11.00.txt
9f658170dc8fd10f42385d9a47793954 readme.11.11.txt
cafbb24f3dc7131501142f75deaeccbd readme.11.22.txt
001522b69a21197098416545749e8584 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.

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 (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.

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.

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* The Software Product Category that this Security Bulletin
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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(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
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extent permitted by law, neither HP nor its affiliates,
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The information in this document is subject to change without
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products referenced herein are trademarks of Hewlett-Packard
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Version: PGP 8.1


Yours truly,
HP S/W Security Team
WTEC Cupertino, California

Return-Path: secure@cup.hp.com
Reply-to: security-alert@hp.com