Download Firefox

Firefox is no longer supported on Windows 8.1 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox is no longer supported on macOS 10.14 and below.

Please download Firefox ESR (Extended Support Release) to use Firefox.

Firefox Privacy Notice

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