A hacker could disrupt Tennessee Valley Authority system , causing blackouts . TVA supplies power to almost 9 million Americans . Comment: Representative : no clear picture of how vulnerable utilities are to cyber attacks .
A hacker could disrupt Tennessee Valley Authority system , causing blackouts . TVA supplies power to almost 9 million Americans . Congress was told 75 percent of utilities fixed problems to combat attacks . Representative : no clear picture of how vulnerable utilities are to cyber attacks .