Computers at two power plants in the US have been infected with malware, according to the US Industrial Control Systems Cyber Emergency Response Team (ICS-CERT), a section of the US Department of Homeland Security.

At one power station, a sophisticated virus was found on three computers, two of them crucial to the plant’s control environment. These workstations had no backup so a failed clean up would have impaired the plant’s operation, according to the latest ICS-CERT newsletter.

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In early October, ten computers at another power company picked up a virus from a USB drive used to upload software updates during a scheduled outage for equipment upgrades. As the computers formed part of the plant’s turbine control system, the restart was delayed by three weeks.

To prevent such incidents, the ICS-CERT recommends maintaining a system of ‘hot spares’ or other backups for critical systems. USB device should be cleaned before each use or replaced with write-once media such as CDs or DVDs.

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