Microsoft 365 security best practices for small businesses

Securing your cloud environment

Microsoft 365 is the engine that runs many small businesses, but it is also a prime target for attackers. Out-of-the-box settings are often designed for ease of use rather than maximum security. Implementing microsoft 365 security best practices is essential to protect your company's sensitive communications and data from phishing, credential theft, and unauthorized access. Hardening your environment is an ongoing task that requires attention to detail.

Implement Multi-Factor Authentication (MFA)

The first and most critical of all microsoft 365 security best practices is to enable multi-factor authentication for every single user. MFA adds a layer of protection that requires users to provide two or more forms of identification before gaining access. This stops nearly all automated password-based attacks. Use 'Conditional Access' policies to make MFA mandatory for all sign-ins, especially for administrators who have high-level access.

Disable Legacy Authentication

Older email protocols like POP3 and IMAP do not support multi-factor authentication. Attackers love these protocols because they can try to guess passwords without being blocked by an MFA prompt. As part of your microsoft 365 security best practices, you should disable these legacy protocols and require all users to use 'Modern Authentication' through apps like Outlook or the Microsoft 365 web portal. This closes one of the most common backdoors used by hackers.

Protect against Phishing and Malware

Microsoft 365 has built-in protections, but they need to be configured correctly to be effective. Enable 'Safe Links' and 'Safe Attachments' if your license level allows it. These features scan links in emails and open attachments in a virtual environment to check for malicious behavior before they reach your employees' inboxes. This proactive scanning is vital for stopping sophisticated phishing attempts.

• Enable anti-phishing policies in the Security & Compliance center.
• Configure 'Safe Links' to protect against malicious URLs in email and Teams.
• Use 'Safe Attachments' to scan for hidden malware in files.
• Train employees to recognize the 'External Sender' warning tag in their inbox.

Apply the Principle of Least Privilege

A common mistake is having too many 'Global Administrators'. If one of these accounts is compromised, the attacker has full control over your entire business. One of the key microsoft 365 security best practices is to limit the number of global admins to between two and four people. Use 'Role-Based Access Control' to give other staff only the specific permissions they need for their jobs, such as 'Helpdesk Administrator' or 'User Administrator.'

Audit your sharing settings

SharePoint and OneDrive allow users to share files easily, but this can lead to data leaks if not managed carefully. Review your external sharing settings to ensure that users are not creating 'Anyone' links that allow anyone with the link to access sensitive company data without logging in. Encourage the use of specific-person sharing instead, which requires the recipient to verify their identity.

1. Review 'Sharing' settings in the SharePoint Admin Center regularly.
2. Limit 'Anyone' links to a short expiration period or disable them entirely.
3. Run a regular report on which files are shared with external users outside the company.
4. Train staff on the difference between internal and external sharing and the risks involved.

Monitor your Microsoft Secure Score

Microsoft provides a tool called 'Secure Score' that analyzes your security posture and suggests improvements. Regularly reviewing this score is one of the easiest microsoft 365 security best practices to follow. It gives you a prioritized list of actions you can take to make your environment more secure, complete with instructions on how to implement them. It's a great way to track your progress over time.

• Turn on MFA for every user in the organization.
• Block all legacy authentication protocols.
• Reduce the number of Global Administrator accounts.
• Configure anti-phishing and anti-malware policies.
• Review and restrict external sharing settings in SharePoint.