Microsoft 365 Security: 5 Smart Ways to Strengthen Your Cyber Defenses

Microsoft 365 plays a central role in driving productivity and collaboration across modern businesses. However, its extensive capabilities come with increased complexity and a broad range of configuration choices, and the default configurations may not offer the best protection for your organization. In a recent Beazley Security webinar, Microsoft Security Consultant Sam Foot highlighted several key areas within the M365 environment that present opportunities for enhancement.  

Why default settings aren’t enough anymore

As companies shift toward cloud-first and hybrid work environments, the traditional network perimeter has faded. Identity has become the new frontline of defense, and attackers are now focusing on user credentials, unmanaged devices, and third-party integrations. In this evolving threat landscape, relying on default settings is no longer enough. Strengthening Microsoft 365 configurations is crucial to maintaining a strong security posture, without compromising the user experience.

5 key areas to strengthen in Microsoft 365

1. Review and adjust default settings

Out-of-the-box settings often prioritize collaboration over control. Features like guest access, app permissions, and tenant creation may be too permissive by default. A quick review and adjustment of these settings can significantly reduce your exposure to risk.

2. Enforce multi-factor authentication (MFA)

MFA remains one of the most effective defenses against unauthorized access. Enabling MFA for everyone, not just admins, and adopting Conditional Access policies can dramatically improve your security. For high-risk accounts, consider phishing-resistant methods like passwordless or certificate-based authentication.

3. Tighten external sharing controls

Collaboration tools like Teams, SharePoint, and OneDrive often allow external sharing by default. To reduce data leakage risks, restrict OneDrive to internal users, configure guest access in SharePoint, and adjust Teams meeting settings to prevent unauthorized participation.

4. Implement conditional access policies

Conditional Access adds intelligence to your authentication process by evaluating user location, device compliance, and real-time risk. This allows you to block suspicious logins or require additional verification when needed, without disrupting legitimate users.

5. Secure personal device access

With BYOD becoming the norm, it’s critical to distinguish between personal and corporate devices. Use mobile application management (MAM), monitor access, and enforce secure device registration to prevent unauthorized data access.

Best practices for ongoing protection

• Regularly review and update your configurations to avoid security drift
• Document changes to maintain visibility into your evolving security posture
• Stay current with Microsoft’s latest security features and updates
• Use built-in tools like Microsoft Secure Score and Compliance Manager to assess and improve your setup

Prioritize quick wins like enabling security defaults or setting up basic Conditional Access policies

Next steps: make security a continuous practice

Default doesn’t mean secure. By proactively optimizing your Microsoft 365 settings, you can close common gaps and build a stronger, more resilient environment. The best part? Many of these improvements are quick to implement and don’t require additional investment.

In today’s threat landscape, securing Microsoft 365 isn’t optional, it’s essential.