From: lists.netsys.com at jscript.dk (Thor Larholm)
Subject: Fw: [VulnWatch] Internet Explorer : The D-Day

----- Original Message -----
From: "GreyMagic Software" <security@...ymagic.com>
To: <vulnwatch@...nwatch.org>
Sent: Tuesday, October 15, 2002 5:19 PM
Subject: [VulnWatch] Internet Explorer : The D-Day


> GreyMagic Security Advisory GM#011-IE
> =====================================
>
> By GreyMagic Software, Israel.
> 15 Oct 2002.
>
> Available in HTML format at http://security.greymagic.com/adv/gm011-ie/.
>
> Topic: Internet Explorer : The D-Day.
>
> Discovery date: 26 Sep 2002.
>
> Affected applications:
> ======================
>
> Microsoft Internet Explorer 5.5 and 6.0; prior versions and IE6 SP1 are
not
> vulnerable.
>
> Note that any other application that uses Internet Explorer's engine
> (WebBrowser control) is affected as well (Outlook under the Internet zone,
> MSN Explorer, etc.).
>
>
> Introduction:
> =============
>
> The <frame> and <iframe> elements may contain URLs in other domains or
> protocols, and therefore have strict security rules, which prevent frames
in
> one domain to access content and information in another. Microsoft
explains
> the issue in this Cross-Frame Scripting article -
>
http://msdn.microsoft.com/workshop/author/om/xframe_scripting_security.asp.
>
> There are several ways to refer to an <iframe>'s (or <frame>) document in
> Internet Explorer (assuming <iframe id="oFrameId">):
>
> * oFrameId.document
> * document.all.oFrameId.contentWindow.document
> * frames.oFrameId.document
> * And others..
>
> All these methods are handled correctly by Internet Explorer and prevent
any
> attempt to access a document that originates from a foreign domain.
>
>
> Discussion:
> ===========
>
> The <iframe> and <frame> elements are really instances of the WebBrowser
> control supplied by Microsoft. The WebBrowser control exposes several
> potentially dangerous properties by default, which Microsoft overrides in
> Internet Explorer.
>
> However, Microsoft missed out on one important property -- "Document",
with
> a capital "D".
>
> Normally, using "oElement.document" would provide a reference to the
> document that owns the current element. The same applies to the <frame>
and
> <iframe> elements. However, we discovered that when
> "oIFrameElement.Document" is used, the returned document is the one
> contained inside the frame, and there are no security restrictions in
place
> to check if it's in a different domain.
>
> This provides free and full access to the frame's Document Object Model,
> which allows an attacker to steal cookies from any site, gain access to
> content in sites (forging content), read local files and execute arbitrary
> programs on the client's machine (script in the "My Computer" zone).
>
> Both Internet Explorer 5.5 SP2 and Internet Explorer 6 are vulnerable, but
> surprisingly this vulnerability does not exist in IE6 SP1. It's hard to
> believe that Microsoft actually meant to plug it as IE5.5 remains
> vulnerable, yet somehow this stray property is now protected.
>
>
> Exploit:
> ========
>
> This exploit demonstrates how an attacker may choose to read the client's
> "google.com" cookie.
>
> <script language="jscript">
> onload=function () {
> // Timer necessary to prevent weird behavior in some conditions
> setTimeout(
> function () {
> alert(document.getElementById("oVictim").Document.cookie);
> },
> 100
> );
> }
> </script>
> <iframe src="http://google.com" id="oVictim"></iframe>
>
>
> Solution:
> =========
>
> Until a patch becomes available either disable Active Scripting or upgrade
> to IE6 SP1.
>
>
> Tested on:
> ==========
>
> IE5.5 Win98.
> IE5.5 NT4.
> IE6 Win98.
> IE6 Win2000.
> IE6 WinXP.
>
>
> Demonstration:
> ==============
>
> We put together four proof-of-concept demonstrations:
>
> * Simple: Reads the client's "google.com" cookie.
> * D-Day Console: Automatically load and execute commands on any site.
> * D-Day Reading: Read local files by accessing a res:// URL.
> * D-Day Execution: Execute arbitrary programs by accessing a res:// URL.
>
> They can all be found at http://security.greymagic.com/adv/gm011-ie/.
>
>
> Feedback:
> =========
>
> Please mail any questions or comments to security@...ymagic.com.
>
> - Copyright ? 2002 GreyMagic Software.
>

Powered by blists - more mailing lists