Microsoft accuses China over email cyber-attacks

US based multinational technology company Microsoft has blamed a Chinese cyber-espionage group for attacks on its mail server software. The tech giant said the hackers belonged to a state-backed group_ which was a "highly skilled and sophisticated actor".

In a blog post_ Microsoft said the hacking campaign made use of four previously undetected vulnerabilities in different versions of the software. The security flaws allowed the hackers to remotely plunder email inboxes.

Microsoft's Threat Intelligence Centre attributed the attacks with "high confidence" to Hafnium_ a group assessed to be state-sponsored and operating out of China. It based its conclusion on "observed victimology_ tactics and procedures".

Microsoft said Hafnium targets infectious disease researchers_ law firms_ higher education institutions and defence contractors. Policy think tanks and non-governmental groups have also been targeted.

This is the eighth time in the past 12 months that Microsoft has publicly disclosed nation-state groups targeting institutions critical to civil society. Although Hafnium is based in China_ it conducts its operations primarily from leased virtual private servers in the US_ Microsoft said.

Separately_ Microsoft said it has observed Hafnium interacting with users of its Office 365 suite. The company has released software updates aimed at addressing the vulnerabilities in its software. Microsoft said the attack was in no way related to the SolarWinds attack_ which hit US government agencies late last year.