the united states is facing an attack threat equivalent to 9/11, an attack that would be carried out by computer. that was the stark warning from defense secretary leon panetta. he described a cyber pearl harbor in which attackers could take over computers that control the transportation system or a utility with deadly consequences. panetta's dire prediction comes after a massive computer attack on the world's largest oil company. so we asked david martin to tell us more. >> reporter: u.s. officials say a cyber attack against aramco, the world's largest oil producer, has been traced to hackers inside iran. another volley in an increasingly high stakes war going on in cyberspace. and defense secretary panetta enns potential enemies, opcluding iran, are developing the capability to launch devastating attacks. >> the collective result of these kinds of attacks could be a cyber pearl harbor. an attack that would cause physical destruction and the loss of life.