Title:      Unchecked buffer in Windows component could cause web
            server compromise (815021)
Date:       17 March, 2003
Software:   Microsoft Windows 2000
Impact:     Run Code of Attacker's Choice
Max Risk:   Critical
Bulletin:   MS03-007

Microsoft encourages customers to review the Security Bulletins
at:
http://www.microsoft.com/technet/security/bulletin/MS03-007.asp
http://www.microsoft.com/security/security_bulletins/ms03-007.asp
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Issue:
======
Microsoft Windows 2000 supports the World Wide Web Distributed
Authoring and Versioning (WebDAV) protocol. WebDAV, defined in
RFC 2518, is a set of extensions to the Hyper Text Transfer
Protocol (HTTP) that provide a standard for editing and file
management between computers on the Internet. A security
vulnerability is present in a Windows component used by WebDAV,
and results because the component contains an unchecked buffer.

An attacker could exploit the vulnerability by sending a
specially formed HTTP request to a machine running Internet
Information Server (IIS). The request could cause the server to
fail or to execute code of the attacker's choice. The code would
run in the security context of the IIS service (which, by
default, runs in the LocalSystem context).

Although Microsoft has supplied a patch for this vulnerability
and recommends customers install the patch immediately,
additional tools and preventive measures have been provided that
customers can use to block the exploitation of this vulnerability
while they are assessing the impact and compatibility of the
patch. These temporary workarounds and tools are discussed in the
"Workarounds" section in the FAQ below.


Mitigating Factors:
====================
 - URLScan, which is a part of the IIS Lockdown Tool will block
this attack in its default configurations
 - The vulnerability can only be exploited remotely if an
attacker can establish a web session with an affected server

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/ms03-007.asp
http://www.microsoft.com/security/security_bulletins/ms03-007.asp

   for information on obtaining this patch.


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