It's not hard to imagine an enemy shutting down our electrical grid, our air traffic control system, our financial system, or our military communications systems with just such a tool. It could be catastrophic, and we wouldn't even know who did it.
Here's an excerpt from the article:
Simply put, Stuxnet is an incredibly advanced, undetectable computer worm that took years to construct and was designed to jump from computer to computer until it found the specific, protected control system that it aimed to destroy: Iran’s nuclear enrichment program.Check out the article at the link.
The target was seemingly impenetrable; for security reasons, it lay several stories underground and was not connected to the World Wide Web. And that meant Stuxnet had to act as sort of a computer cruise missile: As it made its passage through a set of unconnected computers, it had to grow and adapt to security measures and other changes until it reached one that could bring it into the nuclear facility.
When it ultimately found its target, it would have to secretly manipulate it until it was so compromised it ceased normal functions.
And finally, after the job was done, the worm would have to destroy itself without leaving a trace.
That is what we are learning happened at Iran's nuclear facilities -- both at Natanz, which houses the centrifuge arrays used for processing uranium into nuclear fuel, and, to a lesser extent, at Bushehr, Iran's nuclear power plant.