Hackers in recent weeks have exploited flaws in SharePoint, a document management system developed by Microsoft Corp., to try to steal sensitive data from hundreds of victims.

A sweeping cyber espionage operation targeting Microsoft server software compromised about 100 organizations as of the weekend, two of the organizations that helped uncover the campaign said.

The tech giants have evidence that Chinese hackers are exploiting the new bug, but warned "multiple actors" are also hacking into affected SharePoint systems.