When the European head of online security firm McAfee gets a call during vacation, it’s a big deal. In this case, it was the virus Shamoon running rampant through the systems of oil company Saudi Aramco. Forbes contributor Parmy Olson writes about how the virus destroyed 30,000 computers and nearly stopped a big chunk of oil production in the Persian Gulf. Experts fear that calculated cyber-attacks are getting more serious and more widespread.