Software today, especially operating systems, is WELL beyond the point where someone, or even a team of someones, can be sure that all avenues of attack are accounted for. Just like the only way to be sure you won't knock up a girl is to keep your dick in your pants, the only way to be sure a system won't be attacked is to cut it off from any outside contact. Since that's not possible (unless you like expensive, overly-complex paper weights) any system can be compromised. And frankly, when it comes to data security, 1% vulnerability is the same as 100% vulnerability. Like a car alarm, The Club, and other anti-theft measures, you can deter the small-fry, but the big sharks will still get your shit.