Many small and medium-sized businesses (SMBs) use Microsoft 365 (formerly Office 365) thinking it is fully secure right out of the box. However, despite its robust capabilities, the default Microsoft 365 settings leave significant security gaps. Cyber attackers frequently exploit these gaps, potentially exposing your sensitive business data. Here are five quick, high-impact security improvements you can implement immediately to protect your Microsoft 365 environment.

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

Multi-Factor Authentication (MFA) is the single most effective measure you can take to secure user accounts. MFA requires users to verify their identity using a second method beyond just a password—such as a text message, mobile app notification, or biometric verification. Implementing MFA greatly reduces the risk of compromised accounts by making it extremely difficult for attackers to gain unauthorized access.

2. Use Microsoft Defender Preset Security Policies

Microsoft Defender for Office 365 provides built-in security policies—”Standard” and “Strict”—that offer advanced protection against phishing, malware, and malicious attachments. Rather than manually configuring numerous settings, applying these preset policies ensures comprehensive and consistent security across your organization:

• Apply the Strict policy to sensitive accounts.
• Use Standard or Strict for all other users based on their security risk level.

These policies substantially decrease the chances of successful cyberattacks.

3. Implement User and Domain Impersonation Protection

Business Email Compromise (BEC) and phishing attacks commonly involve attackers impersonating trusted individuals or brands. By enabling impersonation protection, Microsoft Defender detects and blocks suspicious emails designed to mimic legitimate contacts or domains. This greatly reduces the risk of fraudulent activity and phishing incidents targeting your business.

4. Restrict External Sharing in SharePoint and OneDrive

By default, SharePoint and OneDrive may allow file sharing with anyone outside your organization, creating opportunities for accidental or malicious data leaks. Strengthen your data security by:

• Allowing sharing only with existing guests or internal users.
• Limiting guest access strictly to the email address invited.
• Setting default permissions to View only rather than Edit.

These simple adjustments significantly reduce the risk of unintended data exposure.

5. Set Up Security Alerts for Suspicious Activities

Even strong prevention measures need support from real-time monitoring. Enable built-in alerts in Microsoft 365 to notify your administrators about potential threats, including:

• Unusual or suspicious sign-in attempts.
• Detection of malware.
• Violations of Data Loss Prevention (DLP) policies.

Regular monitoring of these alerts helps ensure prompt identification and response to threats, minimizing their impact.

Bottom Line: Protect Your Business with Easy-to-Implement Security Measures

Microsoft 365 provides powerful tools to protect your business—but only if you actively configure them. These five straightforward security improvements offer tremendous protection with minimal complexity, helping you secure your business data effectively. SentriSec can help your business easily implement these security measures, ensuring robust, enterprise-level security tailored to SMB needs.

Take action today to ensure your Microsoft 365 environment is secure and resilient against cyber threats.