Privilege escalation using named-functions and redefined "new Object()" — Mozilla

moz_bug_r_a4 discovered that named JavaScript functions have a parent object created using the standard Object() constructor (ECMA-specified behavior) and that this constructor can be redefined by script (also ECMA-specified behavior). If the Object() constructor is changed to return a reference to a privileged object with useful properties it is possible to have attacker-supplied script excuted with elevated privileges by calling the function. This could be used to install malware or take other malicious actions.