REUTERS By Jack Stubbs, Pavel Polityuk and Dustin Volz | MOSCOW/KIEV/WASHINGTON

The virus crippled computers running Microsoft Corp's (MSFT.O) Windows by encrypting hard drives and overwriting files, then demanded $300 in bitcoin payments to restore access. More than 30 victims paid into the bitcoin account associated with the attack, according to a public ledger of transactions listed on blockchain.info.

The White House National Security Council said in a statement there was currently no risk to public safety. The United States was investigating the attack and determined to hold those responsible accountable, it said.

The NSA did not respond to a request for comment. The spy agency has not said publicly whether it built Eternal Blue and other hacking tools leaked online by an entity known as Shadow Brokers.