Joint guidance on Microsoft Exchange Server security best practices – Canadian Centre for Cyber Security
Summary
The Canadian Centre for Cyber Security has joined the US NSA and CISA and Australia’s ASD/ACSC to publish joint guidance on best practices for securing on-premises Microsoft Exchange Server deployments. The guidance stresses prevention and hardening measures — focusing on authentication, encryption, patching and reducing attack surface — to protect sensitive communications and reduce the risk of exploitation.
The publication is intended for administrators of on-prem Exchange servers and points to concrete controls and operational practices to mitigate common compromises and threat actor abuse. The full joint publication (PDF) is linked in the source.
Key Points
- This is a coordinated advisory from the Canadian Centre for Cyber Security, NSA, CISA and ASD/ACSC on Exchange Server security.
- Primary focus is on prevention: hardening servers, keeping software patched and reducing exposure to the internet.
- Strong authentication and encryption are emphasised — implement multi-factor authentication and secure transport where possible.
- Defensive practices include least privilege, network segmentation, backups, and rigorous logging and monitoring.
- Organisations are urged to adopt a proactive posture: apply vendor patches promptly, review external access, and validate recovery procedures.
Content summary
The joint guidance outlines practical security measures for administrators of on-premises Microsoft Exchange Server. It covers technical controls (patching, authentication, TLS), configuration hardening (minimising services, secure defaults), and operational defences (monitoring, backups, incident response). The document is designed to reduce common vectors of compromise and protect the confidentiality and integrity of organisational communications.
Context and Relevance
Microsoft Exchange has been a frequent target for threat actors due to its central role in organisational communications and the sensitivity of mailbox data. Recent incidents and disclosed vulnerabilities have shown how quickly an exposed Exchange instance can be exploited. This joint guidance aligns with broader industry trends emphasising on-premise hardening, reduced attack surface, and resilient operational practices — making it directly relevant to IT and security teams responsible for mail infrastructure.
Why should I read this?
Quick and blunt: if you run Exchange servers, this is worth ten minutes. It’s a concise, authoritative checklist from four major security agencies that tells you what to fix first — MFA, patching, reducing exposure, and better monitoring. Read it now, save yourself an incident later.