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Insomnia : ISVA-100216.1 - Windows URL Handling Vulnerability
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 Insomnia Security Vulnerability Advisory: ISVA-100216.1
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 Name: Windows URL Handling Vulnerability
 Released: 16 February 2010

 Vendor Link:
   http://www.microsoft.com/

 Affected Products:
   Windows 2000, Windows XP, Windows 2003, Windows Vista

 Original Advisory:
   http://www.insomniasec.com/advisories/ISVA-100216.1.htm

 Researcher:
   Brett Moore, Insomnia Security
   http://www.insomniasec.com
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 Description
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A flaw exists with the handling of malformed URL's passed through
the ShellExeute() API. The vulnerability does not directly cause
an issue within Windows itself however, applications that call
the flawed API may be vulnerable to various attacks, one of which
is shown in this report.

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 Details
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The vulnerability is reached when the malformed URL contains #:
and can be used to reference local files.

Two such examples are shown here;
   acrobat://test/#://../../c:/windows/system32/calc.exe
or
   anything://test/#://../../c:/windows/system32/calc.exe

The results will be different dependant on where the URL is used
and which OS platform is in use.

Some examples are shown here;

Start->Run
   Calc.exe is executed without prompt

IE URL Bar or HREF
   User is prompted to execute calc.exe

Word Document
   User is prompted to open acrobat link

PDF Document
   Calc.exe is executed without prompt

Firefox
   Firefox will not follow the URL

Safari
   Calc.exe is executed without prompt

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 Potential Exploit
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Safari will not access the local file through the standard
file:// link, but will execute the local file through the malformed
link.

One method of executable delivery is through the onenote://
URL protocol if Microsoft OneNote is installed.

OneNote will automatically open and process a onenote file shared
over an SMB share. Any executables stored within the onenote file
will be cached locally. This is done by downloading the embedded
executables and storing them in a known location.

C:/Users/[USERNAME]/AppData/Local/Microsoft/OneNote/12.0/OneNoteOfflineCache
_Files/

This file can then be executed through the URL handling vulnerability
leading to an automatic code execution issue through Safari.

Obviously there are some requirements for this exploit;
+ the target user name must be known
+ Microsoft OneNote must be installed
+ SMB access out must be allowed

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 Solution
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Microsoft have released a security update to address this issue;
http://www.microsoft.com/technet/security/Bulletin/MS10-002.mspx
http://www.microsoft.com/technet/security/Bulletin/MS10-007.mspx

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 Legals
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The information is provided for research and educational purposes
only. Insomnia Security accepts no liability in any form whatsoever
for any direct or indirect damages associated with the use of this
information.
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Insomnia Security Vulnerability Advisory: ISVA-100216.1
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