Microsoft Email Servers Hacked, Blames China

The U.S. has issued an emergency warning after Microsoft said it caught China hacking into its mail and calendar server program, called Exchange. The perpetrator, Microsoft said in a blog post, is a hacker group that the company has “high confidence” is working for the Chinese government and primarily spies on American targets. The latest software update for Exchange blocks the hackers, prompting the U.S. Cybersecurity and Infrastructure Security Agency to issue a rare emergency directive that requires all government networks do so.



CISA, the U.S.’s primary defensive cybersecurity agency, rarely exercises its authority to demand the entire U.S. government take protective steps to protect its cybersecurity. The move was necessary, the agency announced, because the Exchange hackers are able “to gain persistent system access.” All government agencies have until noon Friday to download the latest software update. In a separate blog post, Microsoft Vice President Tom Burt wrote that the hackers have recently spied on a wide range of American targets, including disease researchers, law firms and defense contractors. There was no immediate indication that the hack led to significant exploitation of U.S. government computer networks. But the announcement marks the second instance in recent months that the U.S. scrambled to address a widespread hacking campaign believed be the work of foreign government spies.

From the official report:

CISA partners have observed active exploitation of vulnerabilities in Microsoft Exchange on-premises products. Neither the vulnerabilities nor the identified exploit activity is currently known to affect Microsoft 365 or Azure Cloud deployments. Successful exploitation of these vulnerabilities allows an attacker to access on-premises Exchange Servers, enabling them to gain persistent system access and control of an enterprise network.

CISA has determined that this exploitation of Microsoft Exchange on-premises products poses an unacceptable risk to Federal Civilian Executive Branch agencies and requires emergency action. This determination is based on the current exploitation of these vulnerabilities in the wild, the likelihood of the vulnerabilities being exploited, the prevalence of the affected software in the federal enterprise, the high potential for a compromise of agency information systems, and the potential impact of a successful compromise.

Currently, the vulnerabilities related to this known exploitation activity include CVE-2021-26855, CVE-2021-26857, CVE-2021-26858, CVE-2021-27065. According to Microsoft and security researchers, the following vulnerabilities are related yet not known to be exploited: CVE-2021-26412, CVE-2021-26854, CVE-2021-27078.

Read the full report:

Anyone still hosting their own email servers? Might be worth getting back into.