Vulnerability Note VU#143297

Mozilla Firefox allows cross-domain iframe access via JavaScript

Original Release date: 08 Jun 2007 | Last revised: 14 Mar 2008

Overview

Mozilla Firefox allows cross-domain access to an iframe. This vulnerability could allow an attacker to interact with a web site in a different domain. The attacker could read content and cookies, capture keystrokes, and modify content.

Description

An iframe is an HTML element which allows an HTML document to be embedded inside a master HTML document.

The Mozilla same origin policy states:

    The same origin policy prevents document or script loaded from one origin from getting or setting properties of a document from a different origin. The policy dates from Netscape Navigator 2.0.

    Mozilla considers two pages to have the same origin if the protocol, port (if given), and host are the same for both pages.
Firefox does not properly enforce the same origin policy to web pages that use iframes.

From Mozilla Bugzilla Bug ID 382686:
    The problem you fixed there is that document.write() could be used to overwrite frames that originate from Internet-based SRC= pointing to non-same-domain site. This is fixed and throws a security exception.

    Unfortunately, the check implemented means that about:blank frames can be overwritten freely; and unfortunately, *all* frames, even with Internet SRC= specified, will be vulnerable to a race condition while the document loads.
Note that some websites that allow users to supply content may allow iframes to be included.

Impact

An attacker may be able to obtain sensitive data from a user, modify the appearance of a webpage or track keystrokes. Depending on the nature of the web site the user was visiting, this data may include passwords, credit card numbers, and any arbitrary information provided by the user.

Solution

Mozilla has addressed this issue with Firefox 2.0.0.5. Please see Mozilla Foundation Security Advisory 2007-20 for details.

Workarounds for users


Workarounds for administrators
  • Do not allow user submitted content to include JavaScript.
  • Do not allow users to submit content to a shared resource that includes iframes. A shared resource may include the comments section of a blog or a web forum.
  • Monitor the content submitted by third parties for malicious JavaScript or iframes.

Systems Affected (Learn More)

VendorStatusDate NotifiedDate Updated
MozillaAffected-18 Jul 2007
If you are a vendor and your product is affected, let us know.

CVSS Metrics (Learn More)

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

References

Credit

This vulnerability was reported by Michal Zalewski on the Full-Disclosure mailing list.

This document was written by Ryan Giobbi.

Other Information

  • CVE IDs: CVE-2007-3089
  • Date Public: 04 Jun 2007
  • Date First Published: 08 Jun 2007
  • Date Last Updated: 14 Mar 2008
  • Severity Metric: 8.51
  • Document Revision: 52

Feedback

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