Iran has a growing legion of low-grade hackers that are quickly becoming a pain in the side of the Obama administration, and financial companies. 

The U.S. have admitted they believe a series of cyber attacks on domestic banks and some foreign oil companies carried out over the last year are the handiwork of a group of hackers linked to the Iranian government. The prevailing train of thought is the new wave of cyber attacks are a response to U.S. economic sanctions (that are destroying Iran's currency) and the Stuxnet virus that rocked Iran's nuclear program. "They have been going after everyone—financial services, Wall Street," a senior defense official told the Wall Street Journal. "Is there a cyberwar going on? It depends on how you define 'war.'" The administration believes Iran is also behind a number of attacks on U.S. banks. Wells Fargo, Bank of America, JPMorgan and others were all cyber attacked recently. 

Defense Secretary Leon Panetta didn't mince words when he warned of a potential 'cyber Pearl Harbour' during a speech on Thursday night:

“An aggressor nation or extremist group could use these kinds of cyber tools to gain control of critical switches,” Mr. Panetta said. “They could derail passenger trains, or even more dangerous, 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.”

The attacks have, so far, focused on disrupting service to banks via DDOS attacks -- a common hacker trick that tries to overload a website's servers with traffic -- and deleting information. The point of Panetta's remarks are that it could be much worse. The potential danger of Iran, or anyone causing havoc digitally is something the administration knows they have to consider, which is why the government spends $3 billion annually on digital defense.