In a blog post Tuesday, Microsoft said it observed hackers attempting to “gain initial access to target organizations.” According to Microsoft, those involved included hacking groups called Linen Typhoon and Violet Typhoon—which Microsoft said are linked to the Chinese government—and China-based group Storm-2603.

At least three China-based hacking teams have been exploiting a previously unknown flaw in Microsoft SharePoint since at least July 7, the company said in a blog post. Why it matters: Microsoft and security researchers didn't uncover the vulnerability until this past weekend,

A China-linked threat actor has been observed exploiting SharePoint servers to deliver ransomware, according to Microsoft researchers, in the latest sign of worsening attacks against on-premises SharePoint Server customers.