Enhancing Security: A Step-by-Step Guide to Blocking Legacy Authentication in Microsoft 365

Why block Legacy Authentication?

Blocking legacy authentication in Office 365 enhances security by preventing outdated protocols like POP, IMAP, and SMTP from being exploited. These protocols lack modern security features, making accounts vulnerable to attacks like brute force and credential stuffing. It strengthens overall protection.

How to block Legacy Authentication:

1. You first need to go to https://entra.microsoft.com

2. Next, go to Protection > Conditional Access > Policies

3. Call the policy a relevant name

4. Next, Click 'Users' and include 'All users' or create a group for this.

   

5. Next, add the 'Target resources' to 'All cloud apps'

   

6. Next, change the 'conditions' to include the below Client apps:

   

7. Next, go to Access Controls > Grant and enable 'Block access'

   

8. Click 'Enable policy'