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CERT Coordination Center

Microsoft Internet Explorer 6 contains a cross-domain vulnerability

Vulnerability Note VU#923508

Original Release Date: 2008-06-26 | Last Revised: 2008-06-27

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.

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.

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.

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.

Vendor Information

923508
 
Affected   Unknown   Unaffected

Microsoft Corporation

Updated:  June 26, 2008

Status

  Vulnerable

Vendor Statement

No statement is currently available from the vendor regarding this vulnerability.

Vendor Information

The vendor has not provided us with any further information regarding this vulnerability.

Addendum

Please update to Internet Explorer 7 and/or disable Active Scripting.

If you have feedback, comments, or additional information about this vulnerability, please send us email.


CVSS Metrics

Group Score Vector
Base N/A N/A
Temporal N/A N/A
Environmental N/A

References

Credit

This vulnerability was publicly disclosed by rayh4c.

This document was written by Will Dormann.

Other Information

CVE IDs: None
CERT Advisory: CA-2000-02
Severity Metric: 29.84
Date Public: 2008-06-18
Date First Published: 2008-06-26
Date Last Updated: 2008-06-27 12:42 UTC
Document Revision: 14

Sponsored by the Department of Homeland Security Office of Cybersecurity and Communications.