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SSRT4884 rev.3 - 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.

27 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
->action: set ip_pmtu_strategy= 0 and install PHNE_33159

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.

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, B.11.22, and B.11.23.

->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.

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.
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 <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 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
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.11.22,
and B.11.23. A patch is available for B.11.11. The patch
and the 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 patch 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

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.

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
495165288 3646 readme.11.23.txt

md5sum readme*
d28504f8532192de6a4f33bba4ea90ec readme.11.00.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.

->ForB.11.11 download and install PHNE_33159. The patch is
available from .

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 (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.

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:

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System management and security procedures must be reviewed
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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
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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
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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