The U.S. government and its key allies, including the European Union, the U.K., and NATO, formally attributed the massive cyberattack against Microsoft Exchange servers to state-sponsored hacking crews affiliated with the People’s Republic of China’s Ministry of State Security. The sweeping espionage campaign exploited four previously undiscovered vulnerabilities in Microsoft Exchange software and is believed to have hit at least 30,000 organizations in the US and hundreds of thousands more worldwide. Microsoft identified the group behind the hack as a skilled government-backed actor operating out of China named Hafnium.
Source: https://thehackernews.com/2021/07/us-and-global-allies-accuse-china-of.html