- In October 2006, a foreign hacker invaded the Harrisburg, Pa., water filtration system and planted malware.
- In August 2003, the "Slammer" worm infected the Davis Besse nuclear power plant in Ohio, causing a five-hour shutdown of computer systems.
There are also reports overseas, such as the news this week that a major South Korean bank was compromised by a deliberate attack by North Korean hackers sponsored by the rival nation's government. That cyberattack in April left more than 30 million customers without access to their accounts for several days, according to South Korean officials.
As U.S. power systems adopt smart-grid technology, some fear that they, too, will face greater threats.
"What we are doing is laying a new digital infrastructure over the very reliable and sturdy bulk power system," said Mark Weatherford, security chief for the North American Electric Reliability Corporation. "This digital infrastructure provides a lot of new attack vectors into the electrical system that didn't previously exist. Smart meters that exist on homes and businesses and facilities, where it used to be an analog box now is a digital box, which provides new vectors to exploit those networks."