If you’re looking to strengthen your Microsoft 365 cybersecurity, blocking legacy authentication is one of the smartest steps you can take. Legacy authentication protocols (like POP, IMAP, and older versions of Exchange ActiveSync) are much more vulnerable to attacks, making them a frequent target for hackers. With a dedicated Conditional Access policy, you can protect your organization without locking out important users.
Why Is Blocking Legacy Authentication Important?
Microsoft 365 and modern cloud platforms use advanced authentication methods that support features like Multi-Factor Authentication (MFA), but legacy protocols can bypass these protections. That’s why many IT security experts—and Microsoft itself—recommend blocking legacy authentication as a core defense against phishing and brute-force attacks. If your business operates in Canada and wants to stay proactive, Managed IT Security Canada services can help you implement best practices like this quickly and safely.
Step-by-Step Guide: Creating a Conditional Access Policy
Before you start, make sure you’re signed in as at least a Conditional Access Administrator in the Microsoft Entra admin center. Here are the steps to block legacy authentication using Conditional Access:
1. Access Conditional Access Policies
- Go to Protection > Conditional Access > Policies in the Microsoft Entra admin center.
- Select New policy.
2. Name Your Policy
- Give your policy a clear, meaningful name—for example, “Block Legacy Authentication for All Users.”
3. Assign Users
- Under Assignments > Users or workload identities > Include, select All users.
- Under Exclude, choose any accounts or groups that need to keep using legacy authentication (for example, service accounts). Tip: Always exclude at least one admin account to prevent accidental lockout!
4. Select Target Resources
- Under Target resources > Cloud apps > Include, select All cloud apps.
5. Configure Conditions
- Go to Conditions > Client apps and set Configure to Yes.
- Check only Exchange ActiveSync clients and Other clients (these represent legacy apps).
6. Set Access Controls
- Under Access controls > Grant, choose Block access and click Select.
7. Set Policy Mode
- For testing, set Enable policy to Report-only. This lets you see the impact before fully enforcing the block.
8. Create the Policy
- Click Create to finish. Review reports to make sure legitimate users aren’t affected unintentionally.
What’s Next? Moving From ‘Report-only’ to ‘On’
Once you’re confident your policy works as intended, you can set Enable policy to On—making the block live. You can also roll the deployment out to additional groups gradually, minimizing user disruption.
Safe, Managed IT Security for Canada’s Businesses
If you want peace of mind with Microsoft 365 cybersecurity or need expert help with security policies, consider working with professionals like the Cyber Security team at System Support. Our Managed IT Services (Helpdesk) can also support you with daily management and troubleshooting, while our Backup Services (Server & Microsoft 365) ensure your data is always protected—even if a breach is attempted.
Don’t forget: regularly review your security settings, update your backup and continuity plans, and work with IT specialists who understand the latest industry threats. Curious how System Support can keep your business safe? Request a quote today and let’s secure your digital workplace together!
