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TUCoPS :: Windows :: hack7056.htm

Windows SMB Client Transaction Response Handling vuln
EEYE: Windows SMB Client Transaction Response Handling Vulnerability

Windows SMB Client Transaction Response Handling Vulnerability

Release Date:
February 8, 2005

Date Reported:
August 2, 2004

High (Remote Code Execution)


Systems Affected:
Windows 2000
Windows XP
Windows Server 2003

eEye Digital Security has discovered a vulnerability in Windows SMB
client's handling of SMB responses. An attacker who can cause an
affected system to connect to the SMB service on a malicious host may
exploit this vulnerability in order to execute code on the victim's

Technical Details:
The driver MRXSMB.SYS is responsible for performing SMB client
operations and processing the responses returned by an SMB server
service. A number of important Windows File Sharing operations, and all
RPC-over-named-pipes, use the SMB commands Trans (25h) and Trans2 (32h).
A malicious SMB server can respond with specially crafted Transaction
response data that will cause an overflow wherever the data is handled,
either in MRXSMB.SYS or in client code to which it provides data. One
example would be if the file name and short file name length fields in a
Trans2 FIND_FIRST2 response packet can be supplied with inappropriately
large values in order to cause an excessive memcpy to occur when the
data is handled. In the case of these examples an attacker could
leverage file:// links, that when clicked by a remote user, would lead
to code execution.

Retina - Network Security Scanner - has been updated to identify this
Blink - End-Point Vulnerability Prevention - protects from this

Vendor Status:
Microsoft has released a patch for this vulnerability. The patch is
available at: 

Yuji Ukai, Derek Soeder

Related Links:
Retina - Network Security Scanner - 
Blink - End-Point Vulnerability Prevention - 

KiP(he is back), altoids, cretz, hsj, commit(it works well...), Ink,
Rhone, Rose, Mr. White, Chris, Joy, Spot, Alena, Brey, and Cristo.

Copyright (c) 1998-2005 eEye Digital Security Permission is hereby
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to be edited in any way without express consent of eEye. If you wish to
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