Mozilla Foundation Security Advisory 2012-75

select element persistance allows for attacks

October 9, 2012
David Bloom
Firefox, SeaMonkey, Thunderbird
Fixed in
  • Firefox 16
  • SeaMonkey 2.13
  • Thunderbird 16


Security researcher David Bloom of Cue discovered that <select> elements are always-on-top chromeless windows and that navigation away from a page with an active <select> menu does not remove this window.When another menu is opened programmatically on a new page, the original <select> menu can be retained and arbitrary HTML content within it rendered, allowing an attacker to cover arbitrary portions of the new page through absolute positioning/scrolling, leading to spoofing attacks. Security researcher Jordi Chancel found a variation that would allow for click-jacking attacks was well.

In general these flaws cannot be exploited through email in the Thunderbird and SeaMonkey products because scripting is disabled, but are potentially a risk in browser or browser-like contexts in those products.