It’s not affecting just individuals and small businesses.

The study found that nearly 60 percent of businesses hit by ransomware had more than 100 employees, and 25 percent were enterprises with more than 1,000 employees. And about five of every six outbreaks spread from a single employee to at least one coworker, while 47 percent spread to more than 20.

“The threat is getting more significant and more difficult to contain because of the way that this (type) of ransomware is spreading,” Walters said.