US defence secretary Leon Panetta has warned that the country could face a 'cyber-Pearl Harbor' and has drafted new rules which would enable military to move quickly to thwart any such attacks.
Panetta added that digital attacks emanating from foreign soils could paralyse country's power grid financial networks and transportation system saying that a cyber attack had the potential to "paralyse and shock the nation and create a profound new sense of vulnerability".
"They could derail passenger trains loaded with lethal chemicals. They could contaminate the water supply in major cities, or shut down the power grid across large parts of the country," he added
"If we detect an imminent threat of attack that will cause significant physical destruction in the United States or kill American citizens, we need to have the option to take action against those who would attack us, to defend this nation when directed by the president," Panetta told in a speech to business audience in New York.
He also added that the "Shamoon" virus which attacked Saudi Arabia's state oil company, Aramco, was probably the most destructive attack the business sector has seen to date.
"Shamoon included a routine called a 'wiper,' coded to self-execute," Panetta said.
"This routine replaced crucial system files with an image of a burning US flag. It also put additional 'garbage' data that overwrote all the real data on the machine."
In August this year, Saudi Aramco had resumed operating its main internal computer networks after a malicious virus infected about 30,000 of its workstations.
"The new rules will make clear that the Department has a responsibility not only to defend DOD's networks, but also to be prepared to defend the nation and our national interests against an attack in or through cyberspace," Panetta added.
In September this year, Qatar based news broadcaster Al Jazeera's websites were hacked by a group sympathising with Syrian government.
Security researchers have uncovered malware targeting companies in the energy sector - but instead of stealing sensitive information, it looks to disable infected PCs.