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                                    CERT-Renater

                         Note d'Information No. 2008/VULN254
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DATE                      : 27/06/2008

HARDWARE PLATFORM(S)      : /

OPERATING SYSTEM(S)       : Systems running Internet Explorer 6.

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http://www.kb.cert.org/vuls/id/923508
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Vulnerability Note VU#923508

Microsoft Internet Explorer 6 contains a cross-domain vulnerability


Overview

Microsoft Internet Explorer 6 is vulnerable to a cross-domain scripting
violation, which can allow a remote, unauthenticated attacker to access
the content of a web page in a different domain.


I. Description

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 in which zone or domain a
URL exists 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.

Internet Explorer 6 fails to properly enforce the cross-domain security
model when a page location is modified through use of an object, rather
than a string.

Proof-of-concept code that demonstrates this vulnerability is publicly
available.


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.


III. Solution

We are currently unaware of a practical solution to this problem. Please
consider the following workarounds:

Apply an update

This vulnerability does not appear to affect Internet Explorer 7. 
Therefore, updating to Internet Explorer 7 may mitigate this
vulnerability.

Disable Active Scripting

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


Systems Affected

Vendor	Status	Date Updated
Microsoft Corporation	Vulnerable	26-Jun-2008


References

http://www.cert.org/advisories/CA-2000-02.html
http://www.ph4nt0m.org-a.googlepages.com/PSTZine_0x02_0x04.txt
http://secunia.com/advisories/30857/
http://blogs.zdnet.com/security/?p=1348


Credit

This vulnerability was publicly disclosed by rayh4c.

This document was written by Will Dormann.


Other Information
Date Public	06/18/2008
Date First Published	06/26/2008 11:27:57 AM
Date Last Updated	06/27/2008
CERT Advisory	CA-2000-02
CVE Name	
US-CERT Technical Alerts	
Metric	29.83
Document Revision	14

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