HPSBUX01164 SSRT4884 rev.4 - HP-UX TCP/IP Remote Denial of Service (DoS) Jul 19 2005 11:36AM
Security Alert (secure hpchs cup hp com)
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SSRT4884 rev.4 - 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.

10 July 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



HP-UX B.11.22
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.11.23
->action: set ip_pmtu_strategy= 0 and install PHNE_32606

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#532967:

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 and B.11.22.

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.

->Since PHNE_32606 is now available for B.11.23 the preliminary
binary files for B.11.23 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.
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 <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

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
CAN-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 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.11.00 and B.11.22.
Patches are available for 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:
ftp://icmp:icmp (at) hprc.external.hp (dot) com [email concealed]/
or: ftp://icmp:icmp (at) 192.170.19 (dot) 51 [email concealed]/
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.

->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*
2844254744 2546 readme.11.00.txt
2836317466 2469 readme.11.22.txt

md5sum readme*
d28504f8532192de6a4f33bba4ea90ec readme.11.00.txt
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.

For B.11.11 download and install PHNE_33159. The patch is
available from < http://itrc.hp.com>.

->For B.11.23 download and install PHNE_32606. The patch is
available from < http://itrc.hp.com>.

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.

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.

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 (at) hp (dot) com. [email concealed] It is
strongly recommended that security related information being
communicated to HP be encrypted using PGP, especially exploit
information. To obtain the security-alert PGP key please send an
e-mail message to security-alert (at) hp (dot) com [email concealed] with the Subject of
'get key' (no quotes).

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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:
GN = HP General SW,
MA = HP Management Agents,
MI = Misc. 3rd party SW,
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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
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
services; or damages for loss of data, or software restoration.
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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