Computer security experts around the world are racing to patch one of the worst software vulnerabilities discovered in years.

Two men accused of benefiting from the hack Mason Sheppard, 19, of Bognor Regis, U.K., and Nima Fazeli, 22, of Orlando were charged separately in California federal court. The hack alarmed security experts because of the grave potential of such an intrusion for creating geopolitical mayhem with disinformation. The court documents released Friday show how federal agents tracked down the hackers through Bitcoin transactions and by obtaining records of their online chats. Internal Revenue Service investigators in Washington, D.C., identified two of the defendants by analyzing Bitcoin transactions on the blockchain the universal ledger that records Bitcoin transactions that they had sought to make anonymous, federal prosecutors said. ___This story has been corrected to show that participants in the operation, not the hacker identified as Kirk, discussed it with The New York Times.

Hutchins became a national hero under his pseudonym in May 2017, when the North Korean WannaCry worm, which locks computers and finds ways to seek out others to infect, wrecked computers around the world. Working from his parents' house, Hutchins discovered a kill switch to stop WannaCry, halting its spread. The attack cost the UK's National Health Service, which was heavily infected, an estimated 92 million ($114 million) alone. Just three months later, while visiting Las Vegas during hacking conference DEF CON, the FBI arrested and jailed Hutchins. They claimed he helped create Kronos, a less-known malware designed to steal the credentials used to log into bank accounts.