WASHINGTON - Three weeks ago, a debilitating digital virus spread quickly in computer networks at three Southern California hospitals owned by Prime Healthcare Services, encrypting medical and other data so it was impossible to access.
Using a pop-up window, unidentified hackers demanded about $17,000 in the hard-to-trace cybercurrency called bitcoin for the digital key to unlock the data.
The company says it defeated the cyberattack without paying a ransom. But it acknowledged that some patients were temporarily prevented from receiving radiology treatments, and other operations were disrupted briefly while computer systems were down.
The attempted extortion by criminal hackers was the latest case of what the FBI says is a fast-growing threat to vulnerable individuals, companies and low-profile critical infrastructure, like hospitals, schools and local police.
The security breaches - which temporarily disable digital networks but usually don't steal the data - not only have endangered public safety, but revealed a worrying new weakness as public and private institutions struggle to adapt to the digital era.
So-called ransomware attacks have surged so sharply that the FBI says hacking victims in the United States have paid more than $209 million in ransom payments in the first three months of this year, compared with $25 million in all of 2015. The FBI has not reported any arrests.
"Ransomware is a growing threat to businesses and individuals alike," Chris Stangl, a section chief in the FBI's cyber division, said in a statement to the Los Angeles Times.
Companies should train employees not to open digital attachments or to click on unfamiliar web links in emails that might contain viruses or other malware, Stangl said. They also should back up critical data and use up-to-date virus detection software.