Dive Summary:

• Two unnamed U.S. power plants fell victim to a cyber attack according to a report from the U.S. Industrial Control Systems Cyber Emergency Response Team, which is a section of the U.S. Department of Homeland Security.
• The first incident was discovered after two cases of common malware and one sophisticated virus were found on a plant employee's computer.
• The other incident occurred in October 2012 when an infected USB drive damaged the plant's turbine control system, delaying the restart of a plant for three weeks.

From the article:

Several more computers were inspected, and two came up positive for the sophisticated malware. The two computers had no backup, and a failed cleanup would have impaired their operations, the newsletter said.

The report did not say if the computers did or did not have up-to-date antivirus software, but it did say that current software would have found the malware. ...