The Biden administration and its allies have formally accused China of the mass-hacking of Microsoft Exchange servers earlier this year, which prompted the FBI to intervene as concerns rose that the hacks could lead to widespread destruction.
The mass-hacking campaign targeted Microsoft Exchange email servers with four previously undiscovered vulnerabilities that allowed the hackers — which Microsoft already attributed to a China-backed group of hackers called Hafnium — to steal email mailboxes and address books from tens of thousands of organizations around the United States.
Microsoft released patches to fix the vulnerabilities, but the patches did not remove any backdoor code left behind by the hackers that might be used again for easy access to a hacked server. That prompted the FBI to secure a first-of-its-kind court order to effectively hack into the remaining hundreds of U.S.-based Exchange servers to remove the backdoor code. Computer incident response teams in countries around the world responded similarly by trying to notify organizations in their countries that were also affected by the attack.
In a statement out Monday, the Biden administration said the attack, launched by hackers backed by China’s Ministry of State Security, resulted in “significant remediation costs for its mostly private sector victims.”