Urgent Update Alert: Why Keeping Your Exchange Server Current is Essential for EEMS Functionality

If you're an Exchange Server administrator tempted to delay updates, Microsoft's latest advisory should make you pause. The tech giant has issued a critical warning underscoring the importance of keeping Exchange Servers up to date to ensure the continued functionality of the Exchange Emergency Mitigation Service (EEMS).

What is EEMS?

Launched in September 2021, the Exchange Emergency Mitigation Service acts as a rapid response mechanism for Exchange Servers. It automatically applies temporary, emergency mitigations for critical vulnerabilities, shielding organizations from emerging cyber threats until permanent patches are deployed. EEMS depends on connecting to Microsoft's Office Configuration Service (OCS) to retrieve mitigation configurations.

Why is Updating So Important Now?

Microsoft recently announced that "significantly out of date" versions of Exchange Server may soon lose the ability to connect to the OCS due to the deprecation of an older certificate type used by the service. Without this connection, EEMS cannot function effectively, leaving servers vulnerable to attacks. Servers updated with cumulative or security updates released after March 2023 will maintain full EEMS capabilities.

Understanding Microsoft's Update Timeline:

  • March 2023 Security Update: Addressed significant vulnerabilities, including EEMS issues related to TLS certificate updates.
  • Cumulative and Security Updates Post-March 2023: Critical to retain EEMS functionality and protection.

Exchange Server 2019 and 2016 have received multiple updates since March 2023, and staying current ensures your server remains protected and compliant.

What if EEMS Stops Working?

Think of EEMS as your emergency brake system in a car. Without it, you're forced to manually respond to every threat, potentially too late to prevent damage. Without EEMS running, administrators must scramble to deploy manual mitigations, elongating response times and increasing exposure to targeted cyberattacks. Vulnerabilities in unpatched Exchange Servers are often exploited for data breaches, ransomware, and other cyber espionage activities.

Why Microsoft Draws the Line at "Significantly Out of Date"

Servers that haven't installed updates since before March 2023 are labeled "significantly out of date." These lack critical patches essential for defense against evolving threats. Running such outdated servers today is akin to using obsolete antivirus software, highly ineffective against current threats.

The History and Security Context of Exchange Server

Exchange Server has had a history marked by notable security challenges, often favored by malicious actors exploiting unpatched vulnerabilities. Microsoft has postponed the release of new major versions to prioritize resolving these security issues. Exchange Server 2019 stands as the latest version, but only effective if regularly updated.

What Administrators Should Do Now

  1. Check Your Current Version: Use Exchange Admin Center or PowerShell to determine your current CU and SU levels.
  2. Update Immediately: If your server runs versions older than March 2023 updates, upgrade as soon as possible.
  3. Adopt Patch Discipline: Make regular updating a non-negotiable part of your Exchange Server maintenance routine.

In Summary

Regular maintenance of your Exchange Server is not just a best practice—it's critical to ensuring that vital defense mechanisms like EEMS function correctly. Failing to update exposes your organization to increased security risks and operational challenges.

For many organizations, this advisory should serve as a wake-up call to reassess their update strategies or consider modern email solutions in Microsoft 365 to avoid future vulnerabilities.

References:

For continuous updates on Exchange Server security and administration, regularly consult official Microsoft advisories and trusted IT community forums.