[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@xxxxxxxxxxxxxxxxxxxx/
or: ftp://icmp:icmp@xxxxxxxxxxxxx/
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
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(c)Copyright 2005 Hewlett-Packard Development Company, L.P.
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