Microsoft Security Bulletin (MS00-079)
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Patch Available for "HyperTerminal Buffer Overflow" Vulnerability
Originally posted: October 18, 2000
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
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
Affected Software Versions
- Microsoft Windows 98 and Windows 98SE
- Microsoft Windows Me
- Microsoft Windows 2000
- Windows 98 and 98SE:
- Windows Me:
- Windows 2000 (can be applied to both Gold and Service Pack 1):
Note: The above URLs may have been wrapped for readability.
Note: Additional security patches are available at the Microsoft
Please see the following references for more information related to
- Frequently Asked Questions: Microsoft Security Bulletin MS00-079,
- 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
- Microsoft TechNet Security web site,
Obtaining Support on this Issue
This is a fully supported patch. Information on contacting Microsoft
Product Support Services is available at
Microsoft thanks Luciano Martins of USSR Labs (www.ussrback.com) for
reporting this issue to us and working with us to protect customers.
October 18, 2000: Bulletin Created.
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