IE 5.01 vulnerabilities in external.NavigateAndFind()

[joro () NAT BG (Georgi Guninski)]

IE 5.01 vulnerabilities in external.NavigateAndFind()

Disclaimer:
The opinions expressed in this advisory and program are my own and not
of any company.
The usual standard disclaimer applies, especially the fact that Georgi
Guninski
is not liable for any damages caused by direct or  indirect use of the
information or functionality provided by this program.
Georgi Guninski, bears NO responsibility for content or misuse of this
program or any derivatives thereof.

Description:

Internet Explorer 5.01 under Windows 95 and 5.0 under WinNT 4.0 (suppose
other versions are also vulnerable)
allows circumventing "Cross frame security policy" by using
external.NavigateAndFind().
This exposes the whole DOM of the target document.
This allows reading local text and HTML files and files from any host
(suppose reading files of any type is possible), getting cookies (that
is dangerous because may get passwords, etc.) and other sensitive
information.
It is also possible in some cases to read files behind firewall.
This vulnerability may be exploited using HTML email message or a
newsgroup posting.

Details:

window.external.NavigateAndFind() is used to search for strings in
specified URLs displaying the result in a specified frame.
The problem is it allows searching in "javascript:" URLs in a specified
frame.
In this case the code in the "javascript:" URL is executed in the
security context of the target frame
and the code has access to the document loaded in the target frame.
Examine the code below for more information.

The code is:
----------------------------------------------------------------------------------------
<IFRAME NAME="I1" SRC="file://c:/test.txt"></IFRAME>
<SCRIPT>
function f()
{
window.external.NavigateAndFind("javascript:alert(document.body.innerText);","ll","I1");
}
setTimeout("f()",2000);
</SCRIPT>
----------------------------------------------------------------------------------------

Workaround:
Disable Active Scripting

Demonstration is available at http://www.nat.bg/~joro/navan.html

Copyright 1999 Georgi Guninski

Regards,
Georgi Guninski
http://www.nat.bg/~joro