The FBI is investigating whether any U.S. banks were behind a "retaliatory" cyber attack on an Iranian computer network believed to be the launching pad for a 2013 attack on bank websites, Bloomberg reported this week.

Bloomberg didn't identify any specific financial institution being investigated by the FBI, but did say its unnamed sources claimed that JP Morgan executives "advocated such a move in a closed meeting in February 2013."

The bank told the news service that "no action was ever taken," however.

Bloomberg said that private-sector companies in the crosshairs of global hackers are beginning to "push the limits of existing law to consider ways to break into hackers' networks to retrieve stolen data or even knock computers offline to stop attacks."

The risk of suffering an embarrassing and costly attack, like the Sony Pictures hack in late November, has many American companies on edge, Bloomberg cited computer security and law enforcement sources as saying. Many companies are also frustrated that the U.S. government isn't more proactive about protecting their digital assets from hackers.

That's motivating companies to take matters into their own hands, according to Bloombergand not just by playing defense but also considering ways to go on the attack against hacking threats.

"Some companies are enlisting cybersecurity firms, many with military or government security ties, to walk them through options for disrupting hacker operations or peering into foreign networks to find out what intellectual property hackers may have stolen," the news service reported.

Retaliatory, extra-legal strikes by companies which have been hacked against their attackers may already be happening, according to Rep. Michael McCaul (R-Tex), who chairs the House Homeland Security Committee. The Congressman told Bloomberg that "[s]ome victim companies may be conducting offensive operations 'without getting permission' from the federal government."

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