The following is a Security Bulletin from the Microsoft Product Security
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Microsoft Security Bulletin (MS00-070)
Patch Available for Multiple LPC and LPC Ports Vulnerabilities
Originally posted: October 03, 2000
Microsoft has released a patch that eliminates several security
vulnerabilities in Microsoft(r) Windows NT(r) 4.0 and Windows(r)
2000. The vulnerabilities could allow a range of effects, from denial
of service attacks to, in some cases, privilege elevation.
Frequently asked questions regarding this vulnerability and the
patch can be found at
Several vulnerabilities have been identified in the Windows NT 4.0
and Windows 2000 implementations of LPC and LPC ports:
- The "Invalid LPC Request" vulnerability, which affects only
Windows NT 4.0. By levying an invalid LPC request, it would
be possible to make the affected system fail.
- The "LPC Memory Exhaustion" vulnerability, which affects both
Windows NT 4.0 and Windows 2000. By levying spurious LPC
requests, it could be possible to increase the number of
queued LPC messages to the point where kernel memory would
- The "Predictable LPC Message Identifier" vulnerability,
which affects both Windows NT 4.0 and Windows 2000. Any
process that knows the identifier of an LPC message can
access it; however, the identifiers can be predicted. In the
simplest case, a malicious user could access other process'
LPC ports and feed them random data as a denial of service
attack. In the worst case, it could be possible under certain
conditions to send bogus requests to a privileged process in
order to gain additional local privileges
- A new variant of the previously-reported "Spoofed LPC Port
Request" vulnerability. (For more information, please see
This vulnerability affects Windows NT 4.0 and Windows 2000,
and could, under a very restricted set of conditions, allow
a malicious user to create a process that would run under
the security context of an already-running process,
potentially including System processes.
Because LPC can only be used on the local machine, none of these
vulnerabilities could be exploited remotely. Instead, a malicious
user could only exploit them on machines that he could log onto
interactively. Typically, workstations and terminal servers would be
chiefly at risk, because, if normal security practices have been
followed, normal users will not be allowed to log onto critical
servers interactively. This also means that, even in the worst case,
the vulnerability would only confer additional local - not domain -
privileges on the malicious user.
Affected Software Versions
- Microsoft Windows NT 4.0 Workstation
- Microsoft Windows NT 4.0 Server
- Microsoft Windows NT 4.0 Server, Enterprise Edition
- Microsoft Windows NT 4.0 Server, Terminal Server Edition
- Microsoft Windows 2000 Professional
- Microsoft Windows 2000 Server
- Microsoft Windows 2000 Advanced Server
- Microsoft Windows 2000 Datacenter Server
- Microsoft Windows NT 4.0 Workstation, Server, and Server,
- Microsoft Windows NT 4.0 Server, Terminal Server Edition:
To be released shortly
- Microsoft Windows 2000 Professional, Server, Advanced Server,
and Datacenter Server:
Note: The Windows NT 4.0 patch can be installed on systems running
Service Pack 6a, and will be included in Service Pack 7. The Windows
2000 patch can be installed on systems with or without Service Pack
1, and will be included in Service Pack 2.
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 MS00-070,
- Microsoft Knowledge Base article Q266433 discusses this issue
and will be available soon.
- 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 BindView's Razor Team (http://razor.bindview.com)
for reporting these issues to us and helping us protect our
customers. The issues involved in these vulnerabilities required
several months of detailed engineering, and BindView worked closely
with us throughout the process. We'd like to thank them for their
ongoing commitment to responsible reporting practices.
- October 03, 2000: Bulletin Created.
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Last Updated October 03, 2000
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