Microsoft is set to enhance security measures by enabling Windows Extended Protection (EP) by default on servers running Exchange Server 2019, starting in the upcoming fall after the installation of the 2023 H2 Cumulative Update (CU14). EP is a feature designed to bolster Windows Server authentication functionality and counteract authentication relay or “man in the middle” (MitM) attacks.
The Exchange Team announced that EP will be automatically enabled with the CU14 update or later versions. Despite this default setting, administrators can still opt-out using the command-line CU installer.
Microsoft’s recommendation varies depending on the security update a server has installed: For servers with Aug 2022 Security Update (SU) or later with EP enabled, installing CU14 is straightforward.
For those with Aug 2022 SU or later but EP not yet enabled, installing CU14 with the default ‘Enable EP’ option is advised. Servers using Exchange Server versions prior to Aug 2022 SU are encouraged to update immediately to prevent vulnerability. Microsoft had previously introduced EP support for Exchange Server through last year’s August security updates and warned administrators about enabling the feature to fully block potential attacks on affected servers.
The company has also provided a dedicated script for automating EP activation or deactivation across entire Exchange server organizations. Microsoft encourages all customers to enable EP within their environments.
Servers running the August 2022 SU or later are already compatible with EP. Servers older than the August 2022 SU are considered persistently vulnerable and should be updated immediately to prevent potential risks. Additionally, older Exchange servers might encounter communication disruptions with servers that have EP enabled.
In light of the growing importance of securing Exchange servers, Microsoft emphasized the need for customers to keep their on-premises Exchange servers up-to-date by installing the latest supported Cumulative Updates (CU).
This ensures readiness to deploy emergency security patches. The text highlights the significance of Exchange servers as targets for cybercriminals, citing examples like the financially motivated group FIN7, which developed specialized attack platforms to breach Exchange servers. Threat intelligence firm Prodaft’s data reveals the extent of these attacks, with FIN7’s Checkmarks platform already breaching the networks of over 8,000 companies, primarily in the United States.
