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              AUSCERT External Security Bulletin Redistribution
                             
           ESB-2000.195 -- Microsoft Security Bulletin (MS00-054)
        Patch Available for "Malformed IPX Ping Packet" Vulnerability
                                4 August 2000

===========================================================================

	AusCERT Security Bulletin Summary
	---------------------------------

Product:		NWLink
Vendor:			Microsoft
Operating System:	Windows 95
			Windows 98
			Windows 98 SE
Platform:		N/A

Impact:			Denial of Service

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Microsoft Security Bulletin (MS00-054)
- - --------------------------------------

Patch Available for "Malformed IPX Ping Packet" Vulnerability

Date Published: August 03, 2000

Summary
=======
Microsoft has released a patch that eliminates a security
vulnerability  in Microsoft(r) Windows 95, 98 and 98 Second Edition.
The vulnerability  could be used to cause an affected system to fail,
and depending on the  number of affected machines on a network,
potentially could be used to  flood the network with superfluous
data. The affected system component  generally is present only if it
has been deliberately installed.

Frequently asked questions regarding this vulnerability and
the patch can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-054.asp

Issue
=====
The Microsoft IPX/SPX protocol implementation (NWLink) supports the
IPX  Ping command via the diagnostic port 0x456. Because of a flaw in
the  implementation of the protocol in Windows 95, Windows 98 and
Windows 98  Second Edition, NWLink in these systems will respond to
an IPX ping  packet even when the source network address has been
purposely modified  to a broadcast address. This would give a
malicious user an opportunity  to launch an attack by broadcasting a
single ping request - each  affected machine that received the ping
would respond to it,  potentially resulting in a broadcast storm. In
a large network, this  could temporarily swamp the network's
bandwidth. In addition, upon  seeing its own response, each affected
machine would attempt to process  it, triggering a scenario that
would culminate in the machine's  failure. A machine that failed due
to this vulnerability could be put  back into service by rebooting.

IPX is not installed by default in Windows 98 and 98 Second Edition,
and is only installed by default in Windows 95 if there is a network
card present in the machine at installation time. Even when IPX is
installed, a malicious user's ability to exploit this vulnerability
would depend on whether he could deliver a Ping packet to an affected
 machine. Routers frequently are configured to drop IPX packets, and
if  such a router lay between the malicious user and an affected
machine,  he could not attack it. Routers on the Internet, as a rule,
do not  forward IPX packets, and this would tend to protect intranets
from  outside attack, as well as protecting machines connected to the
 Internet via dial-up connections. As discussed in the FAQ, the most
likely scenario in which this vulnerability could be exploited would
be  one in which a malicious user on an intranet would attack
affected  machines on the same intranet, or one in which a malicious
user on the  Internet attacked affected machines on on his cable
modem or DSL  subnet.

Affected Software Versions
==========================
 - Microsoft Windows 95
 - Microsoft Windows 98
 - Microsoft Windows 98 Second Edition

Patch Availability
==================
 - Microsoft Windows 95:
   http://download.microsoft.com/download/win95/Update/8982/
   W95/EN-US/265334US5.EXE
 - Microsoft Windows 98 and Windows 98 Second Edition:
   http://download.microsoft.com/download/win98/Update/8982/
   W98/EN-US/265334USA8.EXE

Note: Line breaks have been inserted into the URLs above for
readability.

Note: Additional security patches are available at the Microsoft
Download Center

More Information
================
Please see the following references for more information related to
this issue.
 - Frequently Asked Questions: Microsoft Security Bulletin MS00-054,
   http://www.microsoft.com/technet/security/bulletin/fq00-054.asp
 - Microsoft Knowledge Base article Q265334 discusses this issue and
   will be available soon.
 - Microsoft TechNet Security web site,
   http://www.microsoft.com/technet/security/default.asp

Obtaining Support on this Issue
===============================
This is a fully supported patch. Information on contacting
Microsoft Technical Support is available at
http://support.microsoft.com/support/contact/default.asp.

Revisions
=========
 - August 03, 2000: Bulletin Created.

- - ------------------------------------------------------------------

THE INFORMATION PROVIDED IN THE MICROSOFT KNOWLEDGE BASE IS PROVIDED
"AS IS" WITHOUT WARRANTY OF ANY KIND. MICROSOFT DISCLAIMS ALL
WARRANTIES, EITHER EXPRESS OR IMPLIED, INCLUDING THE WARRANTIES OF
MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE. IN NO EVENT
SHALL  MICROSOFT CORPORATION OR ITS SUPPLIERS BE LIABLE FOR ANY
DAMAGES  WHATSOEVER INCLUDING DIRECT, INDIRECT, INCIDENTAL,
CONSEQUENTIAL, LOSS  OF BUSINESS PROFITS OR SPECIAL DAMAGES, EVEN IF
MICROSOFT CORPORATION  OR ITS SUPPLIERS HAVE BEEN ADVISED OF THE
POSSIBILITY OF SUCH DAMAGES.  SOME STATES DO NOT ALLOW THE EXCLUSION
OR LIMITATION OF LIABILITY FOR  CONSEQUENTIAL OR INCIDENTAL DAMAGES
SO THE FOREGOING LIMITATION MAY NOT  APPLY.

Last Updated August 03, 2000


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