CISA orders agencies to disconnect Microsoft Exchange on-prem servers

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The Cybersecurity and Infrastructure Security Agency issued an emergency directive on Wednesday requiring all federal civilian agencies to update or disconnect Microsoft Exchange products running on-premises citing an "unacceptable risk" posed by newly discovered vulnerabilities reportedly being weaponized by a threat group with links to China.

"The swiftness with which CISA issued this emergency directive reflects the seriousness of this vulnerability and the importance of all organizations – in government and the private sector – to take steps to remediate it," said acting CISA Director Brandon Wales.

The directive adds that the vulnerabilities are not known to affect Microsoft 365 or Azure Cloud.

"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," according to CISA.

All agency chief information officers are required to submit a report to CISA by noon this Friday outlining their organization's status. The cybersecurity agency will provide a follow-up report to the secretary of Homeland Security and the Office of Management and Budget by April 5.

CISA's directive comes one day after Microsoft began pushing out updates to its Exchange products in response to a state-sponsored group it calls "Hafnium."

A Microsoft blog post published Tuesday said Hafnium targets U.S-based entities from several sectors such as infectious disease researcher, law firms, universities, defense contractors and policy think tanks.

"Even though we've worked quickly to deploy an update for the Hafnium exploits, we know that many nation-state actors and criminal groups will move quickly to take advantage of any unpatched systems. Promptly applying today's patches is the best protection against this attack," according to the blog post.

Microsoft said it has briefed "appropriate U.S. government agencies" on Hafnium. The company also said Hafnium's activity is "in no way connected to the separate SolarWinds-related attack."

About the Author

Justin Katz covers cybersecurity for FCW. Previously he covered the Navy and Marine Corps for Inside Defense, focusing on weapons, vehicle acquisition and congressional oversight of the Pentagon. Prior to reporting for Inside Defense, Katz covered community news in the Baltimore and Washington D.C. areas. Connect with him on Twitter at @JustinSKatz.


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