Last year, the Department of Homeland Security released a scathing report detailing Microsoft’s mistakes during a 2023 hack in which China stole thousands of emails from top government officials. Two years before that, China-linked cyberattackers compromised more than 250,000 Microsoft Exchange servers.

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.

Software giant Microsoft is at the center of cybersecurity storm after China-linked hackers exploited flaws in SharePoint servers to target hundreds of organizations.

A cyber-espionage campaign centered on vulnerable versions of Microsoft's server software now involves the deployment of ransomware, Microsoft said in a late Wednesday blog post.

The US agency responsible for maintaining and designing the nation’s cache of nuclear weapons was among those breached by a hack of Microsoft Corp.’s SharePoint document management software, according to a person with knowledge of the matter.