Ms Neuberger said the FBI was investigating the ransomware used in the attack since October.
“Transnational criminals are most often the perpetrators of these crimes, and they often leverage global infrastructure and global money-laundering networks,” she said.
Ms Neuberger said there was a need for an international campaign to combat ransomware.
“To combat the exploitation of virtual currencies that are often used for payment and ransomware, the US Treasury has also been leading international efforts, including driving development and adoption of virtual assets standards,” she said.
But Ms Neuberger said the US had no advice to victims of the attacks about whether they should pay ransom.