Microsoft Security Bulletin MS03-007: Unchecked buffer in Windows component could cause webserver compromise (815021)

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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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