In what’s one of the more significant series of cyberattacks in 2025, hackers are targeting a severe weakness in Microsoft’s Sharepoint software, which is used by its customers to build and manage shared files. Among the attackers, according to Google security researchers, is a Chinese-affiliated group.

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.