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 number of companies and organizations compromised by a security vulnerability in Microsoft Corp.’s SharePoint servers is increasing rapidly, with the tally of victims soaring more than six-fold in a few days,

In ongoing hacks, Microsoft says it has identified two Chinese hacking groups taking advantage of a key software flaw.