Microsoft Corp. said a Chinese hacking group is exploiting security vulnerabilities in the company’s SharePoint servers to deploy ransomware, following a cyberattack discovered last week that has affected hundreds of entities around the world.

Microsoft is investigating whether a leak from its early alert system for cybersecurity companies allowed Chinese hackers to exploit flaws in its SharePoint service before they were patched, Bloomberg News reported on Friday.

The company said state-backed hacking groups were breaching systems through flaws in SharePoint, which is used by the U.S. government and companies around the world.

The zero-day vulnerability — which was first disclosed late Saturday — has been exploited by several Chinese state-aligned groups, according to Microsoft.

Hackers are exploiting a flaw in a commonly used Microsoft program to gain access to passwords, sensitive data and more.

Federal and state agencies have been plunged into panic after hackers prised open a gap in the armor of a Microsoft program’s security software, researchers have said. At least two unnamed federal agencies,