Chinese hackers targeted groups via server software, says Microsoft

A China-linked cyber-espionage group has been remotely plundering email inboxes using freshly discovered flaws in Microsoft mail server software, the company and outside researchers said on Tuesday — an example of how commonly used programs can be exploited to cast a wide net online.
 
In a blog post, Microsoft said the hacking campaign made use of four previously undetected vulnerabilities in different versions of the software and was the work of a group it dubs HAFNIUM, which it described as a state-sponsored entity operating out of China.
 
In a separate blog post, cyber-security firm Volexity said that in January it had seen the hackers use one of the vulnerabilities to remotely steal “the full contents of several user mailboxes.”