Chinese Hack on Microsoft Poses Imminent Threat to Australian Security: Expert The Australian Cyber Security Centre (ACSC) sounded the alarm on March 3, urging organisations to follow tech giant Microsoft’s instructions to patch vulnerable systems which came under threat by a state-sponsored Chinese cyber attacker. This comes after Microsoft announced on March 2 that a cyber actor based in China, which they called “Hafnium,” hacked its email server software, Microsoft Exchange. The extent of Hafnium’s operations in the United States included the targeting of a multitude of sectors for the purposes of exfiltrating important information. These sectors included infectious disease researchers, law firms, higher education institutions, defense contractors, policy think tanks, and NGOs.