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.

Threat actors exploit SharePoint flaws to access internal systems, steal sensitive data, and carry out surveillance, impersonation, and extortion.

It's not just data theft. A China-based hacking group is using a flaw in vulnerable SharePoint servers to deliver ransomware, Microsoft warns.