L-008: Microsoft HyperTerminal Buffer Overflow

PROBLEM:       Microsoft has identified a vulnerability in the HyperTerminal
               application that is installed, by default, on several Microsoft
               operating systems.
PLATFORM:      Windows 98, 98SE, Windows ME, Windows NT, and Windows 2000
DAMAGE:        The vulnerability may allow a malicious user to execute
               arbitrary code on another user's system.
SOLUTION:      Apply appropriate patches as indicated below.
VULNERABILITY  Risk is MEDIUM. The vulnerability affects system security and
ASSESSMENT:    is publicly known. Patches should be applied as soon as
               possible.


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Microsoft Security Bulletin (MS00-079)
--------------------------------------

Patch Available for "HyperTerminal Buffer Overflow" Vulnerability
Originally posted: October 18, 2000

Summary
=======
Microsoft has released a patch that eliminates a security
vulnerability in the HyperTerminal application that ships with
several Microsoft(r) operating systems. This vulnerability could,
under certain circumstances, allow a malicious user to execute
arbitrary code on another user's system.

Frequently asked questions regarding this vulnerability and the patch
can be found at
http://www.microsoft.com/technet/security/bulletin/fq00-079.asp

Issue
=====
The HyperTerminal application is a utility that installs, by default,
on all versions of Windows 98, 98SE, Windows ME, Windows NT, and
Windows 2000. The product contains an unchecked buffer in a section
of the code that processes Telnet URLs. If a user opened an HTML mail
that contained a particularly malformed Telnet URL, it would result
in a buffer overrun that could enable the creator of the mail to
cause arbitrary code to run on the user's system. Please note that,
although a Telnet URL is involved in this vulnerability, there is no
relationship between this vulnerability and the "Windows 2000 Telnet
Client NTLM Authentication" vulnerability discussed in MS00-067.

HyperTerminal is the default Telnet client on Windows 98, 98SE and
ME. However, it is not the default Telnet client on Windows 2000, and
Windows 2000 users who have not taken steps to make it the default
Telnet client would not be affected by the vulnerability.

Although HyperTerminal ships as part of several Microsoft products,
it was developed by a third party - Hilgraeve, Inc. Additional
information on the vulnerability and a patch for their full version
product, HyperTerminal Private Edition, is available from their web
site at
http://www.hilgraeve.com

Affected Software Versions
==========================
 - Microsoft Windows 98 and Windows 98SE
 - Microsoft Windows Me
 - Microsoft Windows 2000

Patch Availability
==================
 - Windows 98 and 98SE:
   http://download.microsoft.com/download/win98/Update/12395/W98/EN-US/274548USA8.EXE
 - Windows Me:
   http://download.microsoft.com/download/winme/Update/12395/WinMe/EN-US/274548USAM.EXE
 - Windows 2000 (can be applied to both Gold and Service Pack 1):
   http://www.microsoft.com/downloads/release.asp?releaseid=25112

Note: The above URLs may have been wrapped 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 MS00-079,
   http://www.microsoft.com/technet/security/bulletin/fq00-079.asp
 - Microsoft Knowledge Base articles Q274548 (Win9x) and Q276471
   (Win2K) discuss this issue and will be available soon.
 - A patch for HyperTerminal Private Edition (a for-purchase upgrade
   from the default client) is available from
   http://www.hilgraeve.com
 - 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
Product Support Services is available at
http://support.microsoft.com/support/contact/default.asp


Acknowledgments
===============
Microsoft thanks  Luciano Martins of USSR Labs (www.ussrback.com) for
reporting this issue to us and working with us to protect customers.

Revisions
=========
October 18, 2000: Bulletin Created.

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

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