Cross-Site Flashing occurs when user controlled data is not validated and used in
one of the following functions or variables:
In other words, this means that the Flash application must reference external URLs,
and the locations of those URLs are set through user defined parameters (usually Flash Vars).
In order for this vulnerability to be successfully exploited the victim needs to click on
a specially crafted link created by the attacker that will use the vulnerable Flash application
in order to, for example, steal users' credentials.