Mozilla Foundation Security Advisory 2014-20

onbeforeunload and Javascript navigation DOS

Announced

March 18, 2014

Reporter

Tim Philipp Schäfers, Sebastian Neef

Impact

Low

Products

Firefox, SeaMonkey

Fixed in

• Firefox 28
• SeaMonkey 2.25

Description

Security researchers Tim Philipp Schäfers and Sebastian Neef, the team of Internetwache.org, reported a mechanism using JavaScript onbeforeunload events with page navigation to prevent users from closing a malicious page's tab and causing the browser to become unresponsive. This allows for a denial of service (DOS) attack due to resource consumption and blocks the ability of users to exit the application.

References

• hanging tab allows attackers to execute JS for a long time in the background, user is not able to close firefox normal (CVE-2014-1500)