Mozilla Foundation Security Advisory 2011-40

Code installation through holding down Enter

September 27, 2011
Mariusz Mlynski
Firefox, SeaMonkey, Thunderbird
Fixed in
  • Firefox 3.6.23
  • Firefox 7
  • SeaMonkey 2.4
  • Thunderbird 3.1.15
  • Thunderbird 7


Mariusz Mlynski reported that if you could convince a user to hold down the Enter key--as part of a game or test, perhaps--a malicious page could pop up a download dialog where the held key would then activate the default Open action. For some file types this would be merely annoying (the equivalent of a pop-up) but other file types have powerful scripting capabilities. And this would provide an avenue for an attacker to exploit a vulnerability in applications not normally exposed to potentially hostile internet content.

Mariusz also reported a similar flaw with manual plugin installation using the PLUGINSPAGE attribute. It was possible to create an internal error that suppressed a confirmation dialog, such that holding enter would lead to the installation of an arbitrary add-on. (This variant did not affect Firefox 3.6)