Disable Legacy Authentication Part 2

In part one we created a log analytics workspace and used a workbook to identify legacy authentication. In this part we will have a look at how to block legacy auth by using a Conditional Access policy.

Step 1 (communicate). The workbook from part 1 comes useful when we want to identify users still using legacy auth. We can now use sharepoint, teams, yammer e-mail to communicate this with the users, and when we see that the amount of legacy auth sign-ins are little to none to zero it is time to create the CA-policy.

Step 2 (apply CA-policy). Now it is time to create the conditional access (CA) policy to make sure we block legacy auth.

  1. Navigate to “https://portal.azure.com
  2. Click “Azure Active Directory
  3. Click “Security” and “Conditional Access
  4. Click “New policy
  5. Name: “Test – Block Legacy Authentication
  6. Users and groups: “All users” but exclude at least one account just in-case
  7. Cloud apps or actions: “All cloud apps
  8. Conditions: “Yes” and mark both “Exchange ActiveSync clients” and “Other clients
  9. Access controls: Click “Block access
  10. Enable policy: “On
  11. Click: “Create

We have now successfully identified, communicated and blocked legacy authentication!

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