US authorities on Wednesday warned that hackers were trying to infect hospital IT systems with ransomware.
A joint investigation by the Federal Bureau of Investigation (FBI), Cybersecurity and Infrastructure Security Agency (CISA) and the Department of Health and Human Services (HHS) said there was "credible information" hackers were targeting the health care system.
"Malicious actors" were using Ryuk ransomware in attacks that lead to data theft, and the disruption of healthcare services, the authorities said in a joint statement.
The software typically encrypts the contents of computers and demands a ransom to release the data.
A worldwide attack of this kind using the WannaCry ransomware hit British hospitals in May 2017.
Extent of attacks unclear
The exact extent of the current attacks on US hospitals remained unclear.
According to media reports, hospitals in the states of New York, Oregon and Minnesota were affected.
The agencies warned that the attacks could be particularly problematic for the health system as coronavirus cases continue to surge in the US.