Microsoft 365 provides powerful security features for businesses of all sizes. However, simply purchasing Microsoft 365 doesn’t automatically mean your organisation is fully protected.
Many of the most effective security controls require deliberate configuration, ongoing monitoring, and regular review. For small and medium-sized businesses, a few key settings can significantly reduce the risk of account compromise, ransomware, phishing attacks, and accidental data exposure.
Start with Identity Security
In today’s cloud-first world, identity is the new security perimeter.
If an attacker gains access to a Microsoft 365 account, they may be able to access emails, files, Teams conversations, and business applications. That’s why securing identities should be your first priority.
Key areas to review include:
- Multi-Factor Authentication (MFA)
- Administrator account security
- Conditional Access policies
- Inactive user accounts
- Privileged role assignments
Administrators should have separate privileged accounts and avoid using those accounts for everyday email, web browsing, or routine work activities.
The 10-Point Microsoft 365 Security Review
1. Enable MFA for All Users
Multi-Factor Authentication remains one of the most effective ways to prevent account compromise.
Where possible, ensure MFA is enabled for:
- Employees
- Administrators
- Guest accounts
- Third-party access accounts
Security Defaults or Conditional Access policies can help enforce MFA consistently across the organisation.
2. Secure Administrator Accounts
Administrative accounts have elevated permissions and are frequently targeted by attackers.
Best practice includes:
- Dedicated admin accounts
- Least-privilege access
- MFA enforcement
- Regular review of privileged roles
Reducing the number of users with admin rights can dramatically lower risk.
3. Disable Legacy Authentication
Legacy authentication protocols often bypass modern security controls such as MFA.
Review your tenant to identify outdated authentication methods that are no longer required and remove them where possible.
4. Review Email Security Policies
Microsoft 365 includes built-in email protection, but policies should be reviewed to ensure they align with business requirements.
Consider reviewing:
- Anti-spam policies
- Anti-phishing protection
- Email filtering rules
- External sender warnings
Email remains one of the most common attack vectors for businesses, making this area particularly important.
5. Protect Links and Attachments
Many Microsoft 365 licences include advanced protection capabilities that can help identify malicious links and attachments.
If your licensing supports it, review how these protections are configured and ensure they are applied to the users who need them most.
6. Manage Company and Personal Devices
Remote and hybrid working have increased the number of devices accessing business data.
Review:
- Company-managed devices
- Personal devices accessing corporate resources
- Mobile device configurations
- Device compliance requirements
Clear policies and device management controls can help reduce security risks.
7. Encrypt Devices and Monitor Endpoint Health
Lost or stolen devices can create significant security concerns if data is not properly protected.
Businesses should confirm that:
- Device encryption is enabled
- Endpoint protection is active
- Security updates are current
- Device health is monitored regularly
These controls can form an important part of your wider cyber security strategy.
8. Review External Sharing
Microsoft 365 makes collaboration easy, but unrestricted sharing can introduce unnecessary risk.
Regularly check the external sharing settings within:
- SharePoint Online
- OneDrive
- Microsoft Teams
Organisations should ensure sharing permissions are aligned with business needs and regularly reviewed.
9. Enable Auditing and Security Alerts
You can’t respond to security incidents if you don’t know they’re happening.
Review whether your tenant has:
- Auditing enabled
Security alerting configured - Incident response procedures documented
- Alert ownership assigned
Early visibility can significantly reduce the impact of security incidents.
10. Use Secure Score as a Guide
Microsoft Secure Score can highlight opportunities to improve security posture.
However, it’s important not to treat Secure Score as the sole measure of security.
Instead, use it as a prioritisation tool alongside:
- Business risk assessments
- Compliance requirements
- Operational needs
- Available licensing features
The highest score isn’t always the most appropriate outcome for every organisation.
Licensing Matters
Not all Microsoft 365 subscriptions include the same security capabilities.
For example, Business Basic, Business Standard, and Business Premium offer different controls and protection features. Before implementing security recommendations, confirm that your licences support the desired functionality.
Avoid copying security settings directly from another organisation without considering licensing, operational requirements, and recovery processes.
Turn Security Into a Repeatable Process
One-off reviews are useful, but long-term security comes from consistency.
Consider creating a Microsoft 365 security baseline that includes:
- Defined control owners
- Approved exceptions
- Monthly reviews
- Quarterly audits
- Regular evidence collection
This reduces configuration drift and provides confidence when customers, auditors, or insurers ask how your Microsoft 365 environment is protected.
Frequently Asked Questions
Is Microsoft 365 Secure By Default?
Microsoft 365 includes baseline security protections, but additional controls such as MFA, administrator account protection, device management, and secure collaboration settings should be reviewed and configured appropriately.
Should We Aim for a Perfect Secure Score?
Not necessarily.
Secure Score should be used as a guide to identify improvements. Prioritisation should be based on business risk, compliance obligations, and the practical needs of your organisation.
Final Thoughts
Microsoft 365 offers a strong security foundation, but achieving the best protection requires more than simply enabling a few settings.
By regularly reviewing identity controls, administrator accounts, device security, email protection, external sharing, and monitoring capabilities, SMEs can significantly improve their resilience against modern cyber threats.
Need Help Securing Microsoft 365?
At Cyber Chameleon, we help businesses assess their Microsoft 365 security posture, identify weaknesses, and implement practical improvements that balance usability with protection.
Book a free consultation to understand how secure your Microsoft 365 environment really is.