SAN FRANCISCO — The massive ransomware attack that crippled more than 20% of hospitals in the United Kingdom and disabled systems in as many as 74 countries appears to have been inadvertently stopped by a 22-year-old computer security researcher in England who began studying it Friday afternoon.

The story, which the as-yet-unnamed security whiz wrote up in a blog post on Saturday, is an example of the driven-to-puzzle-things-out mentality typical of people drawn to cybersecurity.

“He was in the right place at the right time, and he did the right thing without any hesitation,” said Dan Kaminsky, a longtime security researcher and chief scientist at White Ops, a New York-based based security firm.

Because nobody's really in charge of the Internet, it's messy and wonderful in equal proportion, he said.

"We maintain it with duct tape, baling wire and the good graces of no small number of 'volunteer firefighters.' I am hopeful for a future with more formal, funded support for this foundation of our suddenly global information economy. But it's pretty great that a 22-year-old can see a worldwide problem and spend a bit to help us all,” Kaminsky said.