Microsoft’s release of patches for multiple different on-premises Microsoft Exchange Server zero-day vulnerabilities that are being exploited by a nation-state affiliated group.
The vulnerabilities exist in on-premises Exchange Servers 2010, 2013, 2016, and 2019. Exchange Online is not affected. We wanted to ensure you were aware of the situation and would ask that you help drive immediate remediation steps. https://www.microsoft.com/security/blog/2021/03/02/hafnium-targeting-exchange-servers/ for more information.
Specifically, to minimize or avoid impacts of this situation, Microsoft highly recommends that you take immediate action to apply the patches for any on-premises Exchange deployments you have or are managing for a customer or advise your customer of the steps they need to take. The first priority being servers which are accessible from the Internet (e.g., servers publishing Outlook on the web/OWA and ECP).
To patch these vulnerabilities, you should move to the latest Exchange Cumulative Updates and then install the relevant security updates on each Exchange Server.
- You can use the Exchange Server Health Checker script, which can be downloaded from GitHub (use the latest release).
- Running this script will tell you if you are behind on your on-premises Exchange Server updates (note that the script does not support Exchange Server 2010).
- We also recommend that your security team assess whether or not the vulnerabilities were being exploited by using the Indicators of Compromise we shared here.
Microsoft Exchange Server 2010 – UR 31 – https://www.microsoft.com/en-us/download/details.aspx?id=102519
Microsoft Exchange Server 2013 Cumulative Update 23 – Security Update
Microsoft Exchange Server 2016 Cumulative Update 19 – Security Update
Microsoft Exchange Server 2019 Cumulative Update 8 – Security Update
Please get in touch if you require any help with this issue.