Cracking Stuxnet, a 21st-century cyber weapon

When first discovered in 2010, the Stuxnet computer worm posed a baffling puzzle. Beyond its sophistication loomed a more troubling mystery: its purpose. Ralph Langner and team helped crack the code that revealed this digital warhead's final target. In a fascinating look inside cyber-forensics, he explains how -- and makes a bold (and, it turns out, correct) guess at its shocking origins.