McAfee, Inc.
McAfee Avert™ Labs Security Advisory
Public Release Date: 2006-05-09

Microsoft MSDTC NdrAllocate Validation Vulnerability

CVE-2006-0034
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•	Synopsis

There is an RPC procedure within the MSDTC interface in msdtcprx.dll
that may be called remotely without user credentials in such a way that
triggers a denial-of-service in the Distributed Transaction Coordinator
(MSDTC) service.

Exploitation can at most lead to a denial of service and therefore the
risk factor is at medium.
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•	Vulnerable Systems

Microsoft Windows 2000
Microsoft Windows XP
Microsoft Windows Server 2003

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•	Vulnerability Information

The msdtcprx.dll shared library contains RPC procedures for use with
the Distributed Transaction Coordinator (MSDTC) service utilized in
Microsoft Windows.

By sending a large (greater than 4k) request to BuildContextW(), a
size check can be bypassed and a bug in NdrAllocate() may be reached.

This vulnerability was reported to Microsoft on October 12, 2005

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•	Resolution

Microsoft has provided a patch for this issue.  Please see their 
bulletin, KB913580, for more information on obtaining and installing
the patch.


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•	Credits

This vulnerability was discovered by Chen Xiaobo of McAfee Avert Labs.

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•	Legal Notice

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