Mozilla Firefox fails to properly handle JavaScript onUnload events

Overview

Mozilla Firefox does not properly handle JavaScript onUnload events. This vulnerability may lead to memory corruption that could allow a remote, unauthenticated attacker to execute arbitrary code on a vulnerable system.

Description

The JavaScript onUnload event is executed when the browser exits a web page. An event handler can be installed via JavaScript to trap and process this event.

Mozilla Firefox fails to properly handle JavaScript onUnload events. Specifically, Firefox may not correctly handle freed data structures modified in the onUnload event handler, which could cause memory corruption.

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Impact

By convincing a user to view a specially crafted HTML document (e.g., a web page or an HTML email message or attachment), an attacker may be able to execute arbitrary code with the privileges of the user.

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Solution

Upgrade
Firefox has addressed this issue in Firefox version 2.0.0.2 as well as Firefox 1.5.0.10. See Mozilla Foundation Security Advisory 2007-08 for more information

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Disable JavaScript

Disabling JavaScript will prevent exploitation of this vulnerability. For instructions on disabling JavaScript in Mozilla Firefox, refer to the Mozilla Firefox section the Securing Your Web Browser document.

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Vendor Information

393921

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Updated: February 26, 2007

Status

Affected

Vendor Statement

We have not received a statement from the vendor.

Vendor Information

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

Addendum

Refer to <http://www.mozilla.org/security/announce/2007/mfsa2007-08.html&gt;.

If you have feedback, comments, or additional information about this vulnerability, please send us [email](<mailto:[email protected]?Subject=VU%23393921 Feedback>).

CVSS Metrics

Group	Score	Vector
Base
Temporal
Environmental

References

• <http://www.mozilla.org/security/announce/2007/mfsa2007-08.html&gt;
• <https://bugzilla.mozilla.org/show_bug.cgi?id=371321&gt;
• <http://secunia.com/advisories/24333/&gt;
• <http://secunia.com/advisories/24384/&gt;
• <http://secunia.com/advisories/24432/&gt;

Acknowledgements

This vulnerability was publicly disclosed by Michal Zalewski.

This document was written by Jeff Gennari.

Other Information

CVE IDs:	CVE-2007-1092
Severity Metric:	18.36 Date Public: