The BBC has an article detailing a "serious" flaw in OSX that would allow hackers in article Now I may not understand this fully, but as I read it this says that: A user can download a file that claims to be, let's say, a JPG, but it is actually an application and that OSX will treat it as an application. Now my understanding of OSX is that: 1. Unless you have rights to do so you cannot install applications. 2. Even if you are in the admin account it will ask you to confirm that you want to activate the application. So, if you were expecting a JPG and get an app then on your head be it if you activate it. How could Apple write an OS that can overcome this? The only other, more secure scenario I can imagine is that the OS checks the code and tells you that it is not particularly nice because of a list of reasons that it considers unwelcome. But that is asking TOO much in my opinion.