Reminds me of several movie plots, and equally plausible.
One of the more popular scenarios for film and book plots involves a nasty germ developed by some government as a bio-weapon. Since microorganisms can't distinguish Friend from Enema (heh) the killer bug escapes into the wild and starts killing everyone. It's entirely plausible, because we know governments really can be that myopic.
The same thing is happening for real with cyber-war. Stuxtnet thankfully can't KILL you, but it totally validates the "short-sighted government program to create indiscriminate weapons" model.
So who' going to make us a film about a future Stuxtnet that destroys the world's computing systems and brings down civilization as we know it?