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                                    CERT-Renater

                         Note d'Information No. 2006/VULN363
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DATE                      : 29/06/2006

HARDWARE PLATFORM(S)      : /

OPERATING SYSTEM(S)       : Systems running Microsoft Internet Explorer.

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US-CERT Vulnerability Note VU#883108
Microsoft Internet Explorer HTML Document object cross-domain vulnerability

Detail
======

Overview

	Microsoft Internet Explorer contains a cross-domain vulnerability in
	how it handles redirected object data. This could allow an attacker
	to access the content of a web page in a different domain.

I. Description

	The Cross-Domain Security Model

	IE uses a cross-domain security model to maintain separation between
	browser frames from different sources. This model is designed to
	prevent code in one domain from accessing data in a different domain.
	The Internet Security Manager Object determines which zone or domain
	a URL exists in and what actions can be performed. From Microsoft
	Security Bulletin MS03-048:

	One of the principal security functions of a browser is to ensure
	that browser windows that are under the control of different Web sites
	cannot interfere with each other or access each other's data, while
	allowing windows from the same site to interact with each other. To
	differentiate between cooperative and uncooperative browser windows,
	the concept of a "domain" has been created. A domain is a security
	boundary - any open windows within the same domain can interact with
	each other, but windows from different domains cannot. The cross-domain
	security model is the part of the security architecture that keeps
	windows from different domains from interfering with each other.

	The HTML Document object

	The HTML Document object provides the core HTML rendering functionality
	of the Internet Explorer web browser. This object is provided by the
	file mshtml.dll. A web page can make use of the HTML Document object
	as an ActiveX control by using the <OBJECT> tag.

	The problem

	The HTML Document object fails to enforce the cross-domain security
	model when it encounters an HTTP redirect.

II. Impact

	By convincing a user to view a specially crafted HTML document (e.g.,
	a web page or an HTML email message), an attacker may be able to
	obtain access to web content in another domain. The impact is similar
	to that of a cross-site scripting vulnerability. For a more detailed
	description of the impact of cross-site scripting vulnerabilities,
	please see CERT Advisory CA-2000-02.
	http://www.cert.org/advisories/CA-2000-02.html#impact

III. Solution

	We are currently unaware of a practical solution to this problem.

	Disable ActiveX

	This vulnerability can be mitigated by disabling ActiveX, as specified
	in the "Securing Your Web Browser" document.

Systems Affected

	Vendor                  Status      Date Updated
	Microsoft Corporation   Vulnerable  28-Jun-2006

References

	http://www.us-cert.gov/reading_room/securing_browser/#Internet_Explorer
	http://lists.grok.org.uk/pipermail/full-disclosure/attachments/20060627/3d930eda/PLEBO-2006.06.16-IE_ONE_MINOR_ONE_MAJOR.obj
	http://secunia.com/advisories/20825/
	http://isc.sans.org/diary.php?storyid=1448&rss
	http://www.w3.org/Protocols/rfc2616/rfc2616-sec10.html#sec10.3

Credit

	This vulnerability was publicly disclosed by Plebo Aesdi Nael.

	This document was written by Will Dormann.
	Other Information
	Date Public	06/27/2006
	Date First Published 06/28/2006 03:17:02 PM
	Date Last Updated	06/28/2006
	CERT Advisory	
	CVE Name	
	Metric 11.34
	Document Revision	6

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