Jim Finkle for Reuters:  A U.S. government cyber security official warned that authorities have seen an increase in attacks that penetrate industrial control system networks over the past year, and said they are vulnerable because they are exposed to the Internet.

Industrial control systems are computers that control operations of industrial processes, from energy plants and steel mills to cookie factories and breweries.

“We see more and more that are gaining access to that control system layer," said Marty Edwards, who runs the Department of Homeland Security's Industrial Control Systems Cyber Emergency Response Team, or ICS-CERT.

ICS-CERT helps U.S. firms investigate suspected cyber attacks on industrial control systems as well as corporate networks.

Interest in critical infrastructure security has surged since late last month when Ukraine authorities blamed a power outage on a cyber attack from Russia, which would make it the first known power outage caused by a cyber attack.  Cont'd...