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

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.