Ghost hackers infiltrating the computers of Tibetan exiles and the U.S. electric grid have pulled the curtain back on 21st-century espionage as nefarious as anything from the Cold War — and far more difficult to stop. Nowadays, a hacker with a high-speed Internet connection, knowledge of computer security and some luck can pilfer information thought to be safely ensconced in a digital locker. The threat is growing, with countries — including the U.S. — pointing fingers at each other even as they ramp up their own cyber espionage.
