Microsoft 365 is one of the most widely used productivity platforms in the world, but with convenience comes risk. Many businesses overlook the simple, built-in features that can significantly improve their security posture. At Commercial Networks, we help organisations implement quick win security measures that immediately reduce vulnerabilities and strengthen defences.
Here are some practical steps you can take today to improve Microsoft 365 security.
Enable Multi-Factor Authentication
Passwords alone are no longer enough. If a username and password are guessed, stolen, or leaked on the dark web, attackers can gain access instantly. Multi-Factor Authentication (MFA) adds an extra layer of protection by requiring a second form of verification, such as a text code or approval via an app.
By enabling MFA for all accounts, and enforcing it on administrator accounts via security defaults, you make it far harder for cybercriminals to gain unauthorised access.
Use Session Timeouts
Employees often forget to log out of accounts or lock devices. This can leave sensitive systems exposed to anyone with physical access. Session timeouts automatically lock a device or account after inactivity, preventing hackers from hijacking unattended sessions.
Manage Calendar Sharing Carefully
Shared calendars are excellent for collaboration, but they can also reveal opportunities to attackers, for instance, showing when IT administrators are out of office. Review calendar-sharing permissions and restrict what information is visible to external users.
Advanced Threat Protection
Traditional antivirus and firewalls are no longer enough. Microsoft Advanced Threat Protection (ATP) provides real-time protection against sophisticated threats like phishing and ransomware. Powered by machine learning, ATP analyses emails, attachments, and links against a constantly updated threat database.
It’s like having a security specialist watching over your machine 24/7.
Policy Alerts in Microsoft 365
Policy alerts in the Microsoft 365 compliance centre allow organisations to educate users in real time. For example, if an employee tries to send sensitive data externally, a warning can appear with guidance.
This not only reduces the chance of accidental leaks but also teaches staff better security habits over time.
Secure Mobile Access
Smartphones are now central to working life, so protecting them is critical. Using Microsoft’s mobile device management (MDM) tools, businesses can enforce security policies, manage permissions, and even remotely wipe lost or stolen devices to prevent data loss.
Deactivate Legacy Protocol Authentication
Older authentication protocols do not support modern security features such as MFA. They’re a favourite target for attackers. Disable legacy protocols wherever possible, or restrict them to service accounts that absolutely require them.
Role-Based Access Control
Not every employee needs access to all data. Role-based access control (RBAC) ensures only the right people can access the right information. For instance, directors’ files can be restricted to senior staff only.
Unified Audit Log
Enabling the Unified Audit Log (UAL) in Microsoft 365 brings together logs from services like SharePoint, OneDrive, and Teams. These logs can be integrated into a SIEM (Security Information and Event Management) tool, giving administrators visibility into suspicious activity and enabling faster responses to threats.
Encrypt Emails
If email accounts are compromised, unencrypted messages are a goldmine for attackers. Enabling email encryption makes sensitive data unreadable to unauthorised users, reducing the impact of breaches.
Train Employees Continuously
Even the best security measures can be undone by human error. Continuous cybersecurity awareness training teaches staff to spot phishing attempts, avoid unsafe behaviour, and report suspicious activity. For new employees, training should begin before access to sensitive systems is granted.
Conclusion
Securing Microsoft 365 doesn’t need to be complex. By applying these quick win security measures, organisations can significantly reduce their risk of breaches and strengthen day-to-day resilience.
At Commercial Networks, we automatically implement many of these defences for our clients through our Shield package, giving peace of mind that systems are properly protected.
📞 Call us on 0333 444 3455 or email sales@cnltd.co.uk to discuss how we can secure your Microsoft 365 environment today.
