5 Essential Security Measures for Microsoft 365 You Shouldn't Ignore

5 Essential Security Measures for Microsoft 365 You Shouldn't Ignore

Microsoft 365 is a powerful cloud platform, but with great power comes great responsibility—especially when it comes to security. Whether you're managing a small business or a large enterprise, it's crucial to implement baseline security best practices to protect your users, data, and operations.

Here are five essential steps every Microsoft 365 administrator should take to harden their environment:

1. Ensure Microsoft 365 Audit Log Search Is Enabled

Audit logging is your first line of defense when it comes to visibility into user and admin activity. Without it, you’re essentially flying blind.

Why it matters: The Unified Audit Log captures a wide range of events across Exchange, SharePoint, Teams, Azure AD, and more. If a breach or suspicious behavior occurs, the audit log is often your best tool for investigating what happened and when.

What to do: Go to the Microsoft Purview compliance portal and verify that audit log search is turned on. Microsoft has started enabling this by default in many tenants, but it’s still worth checking—especially for older environments.

2. Ensure Two Emergency Break Glass Accounts Have Been Created

Break glass accounts are highly privileged admin accounts that are exempt from conditional access policies. They’re your emergency lifeline.

Why it matters: If your Conditional Access or MFA policies lock out all admins (yes, it happens more often than you think), break glass accounts allow you to regain control without downtime or support escalation.

Best practice:

• Create at least two Global Admin break glass accounts.

• Configure them to use phishing-resistant MFA with something like a YubiKey.

• Store security keys securely (e.g., in a physical safe).

• Exclude them from all Conditional Access policies.

• Monitor usage of these accounts.

3. Enable Multi-Factor Authentication (MFA) for All Users

MFA is one of the simplest and most effective ways to prevent unauthorized access—even if a user’s password is compromised.

Why it matters: Microsoft data shows that MFA can block over 99% of identity-based attacks. Yet many organizations still leave it disabled for regular users.

What to do: Enforce MFA using Conditional Access policies or security defaults. You can roll it out gradually, but the end goal should be 100% MFA coverage for all users.

Best practice:

• Target "All Users" and "All Resources". Exclude admins and cover them in their own separate policy.

• Do not exclude on-premises locations.

4. Enable MFA for Admins

While MFA for all users is important, admins are the highest-value targets and should be prioritized.

Why it matters: Admin accounts have the keys to your kingdom. A compromised admin can wreak havoc—deleting data, creating backdoors, or disabling security controls.

Best practice: Use a dedicated Conditional Access policy that enforces stronger MFA methods (like passwordless or phishing-resistant options) for Global Administrators and other privileged roles.

Best practice:

• Target all admin directory roles—excluding directory synchronization roles (if applicable).

• Do not exclude on-premises locations.

• Create separate, unique, and cloud-only admin accounts for your admins to use.

• Admins should reauthenticate at least every 4 hours and should reauthenticate when they close and re-open their browser.

5. Ensure Email Threat Policies Meet Standard Preset Minimum Requirements

Email remains a top vector for phishing and malware. Microsoft Defender for Office 365 includes powerful protection, but only if it’s configured properly.

Why it matters: Default policies may not be enough. You should ensure your anti-phishing, anti-spam, and anti-malware policies meet or exceed Microsoft's Standard Preset Security Policies.

What to do: In the Microsoft 365 Defender portal, verify that:

• Your policies are in place and assigned to all users licensed for Defender for Office 365 (we recommend Plan 2).

• Settings match or exceed the "Standard Preset" baseline.

• Alerts and reporting are actively monitored.

Final Thoughts

Security in Microsoft 365 isn't just about reacting to incidents—it's about being proactive. By enabling audit logging, securing admin access, enforcing MFA, and optimizing email threat protection, you’re laying a solid foundation for a resilient, secure cloud environment.

Hire Redeemer Cyber to perform a Microsoft 365 Security Assessment for you today!

Contact us at www.redeemercyber.com