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Title: Buffer Overrun In RPCSS Service Could Allow Code
Execution (824146)
Date: September 10, 2003
Software: Microsoft Windows NT Workstation 4.0
Microsoft Windows NT Server(r) 4.0
Microsoft Windows NT Server 4.0, Terminal Server
Edition
Microsoft Windows 2000
Microsoft Windows XP
Microsoft Windows Server 2003
Impact: Run code of attacker's choice
Max Risk: Critical
Bulletin: MS03-039

Microsoft encourages customers to review the Security Bulletins
at:

http://www.microsoft.com/technet/security/bulletin/MS03-039.asp
http://www.microsoft.com/security/security_bulletins/MS03-039.asp

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Issue:

The fix provided by this patch supersedes the one included in
Microsoft Security Bulletin MS03-026.

Remote Procedure Call (RPC) is a protocol used by the Windows
operating system. RPC provides an inter-process communication
mechanism that allows a program running on one computer to
seamlessly access services on another computer. The protocol
itself is derived from the Open Software Foundation (OSF) RPC
protocol, but with the addition of some Microsoft specific
extensions.

There are three identified vulnerabilities in the part of RPCSS
Service that deals with RPC messages for DCOM activation- two
that could allow arbitrary code execution and one that could
result in a denial of service. The flaws result from incorrect
handling of malformed messages. These particular vulnerabilities
affect the Distributed Component Object Model (DCOM) interface
within the RPCSS Service. This interface handles DCOM object
activation requests that are sent from one machine to another.

An attacker who successfully exploited these vulnerabilities
could be able to run code with Local System privileges on an
affected system, or could cause the RPCSS Service to fail. The
attacker could then be able to take any action on the system,
including installing programs, viewing, changing or deleting
data, or creating new accounts with full privileges.

To exploit these vulnerabilities, an attacker could create a
program to send a malformed RPC message to a vulnerable system
targeting the RPCSS Service.

Microsoft has released a tool that can be used to scan a network
for the presence of systems which have not had the MS03-039 patch
installed. More details on this tool are available in Microsoft
Knowledge Base article 827363. This tool supersedes the one
provided in Microsoft Knowledge Base article 826369. If the tool
provided in Microsoft Knowledge Base Article 826369 is used
against a system which has installed the security patch provided
with this bulletin, the superseded tool will incorrectly report
that the system is missing the patch provided in MS03-026.
Microsoft encourages customers to run the latest version of the
tool available in Microsoft Knowledge Base article 827363 to
determine if their systems are patched.

Mitigating Factors:

• Firewall best practices and standard default firewall
  configurations can help protect networks from remote attacks
  originating outside of the enterprise perimeter. Best practices
  recommend blocking all ports that are not actually being used.
  For this reason, most systems attached to the Internet should
  have a minimal number of the affected ports exposed.

Risk Rating:

• Critical

Patch Availability:

• A patch is available to fix this vulnerability. Please read
  the Security Bulletins at

http://www.microsoft.com/technet/security/bulletin/MS03-039.asp
http://www.microsoft.com/security/security_bulletins/MS03-039.asp

for information on obtaining this patch.

Acknowledgment:

• eEye Digital Security (http://www.eeye.com/html)
• NSFOCUS Security Team (http://www.nsfocus.com)
• Xue Yong Zhi and Renaud Deraison from Tenable Network Security
  (http://www.tenablesecurity.com)

for reporting the buffer overrun vulnerabilities and working with
us to protect customers.

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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.

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