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CISA has issued supplemental direction to Emergency Directive (ED) 21-02: Mitigate Microsoft Exchange On-Premises Product Vulnerabilities providing additional forensic triage and server hardening, requirements for federal agencies. Specifically, this update directs federal departments and agencies to run newly developed tools —Microsoft’s Test-ProxyLogon.ps1 script and Safety Scanner MSERT—to investigate whether their Microsoft Exchange Servers have been compromised.  

Although the Emergency Directive only applies to Federal Civilian Executive Branch agencies, CISA encourages state and local governments, critical infrastructure entities, and other private sector organizations to review the supplemental direction and the following resources for additional information:

• CISA Emergency Directive 21-02: Mitigate Microsoft Exchange On-Premises Product Vulnerabilities
• CISA Alert AA21-062A: Mitigate Microsoft Exchange Server Vulnerabilities
• CISA web page: Remediating Microsoft Exchange Vulnerabilities
• Microsoft’s EOMT.ps1 blog post