Conditional Access: Require MFA for all users

As Alex Weinert, the Directory of Identity Security at Microsoft, mentions in his blog post Your Pa$$word doesn't matter:

Your password doesn’t matter, but MFA does! Based on our studies, your account is more than 99.9% less likely to be compromised if you use MFA.

The guidance in this article will help your organization create a balanced MFA policy for your environment.

User exclusions

Conditional Access policies are powerful tools, we recommend excluding the following accounts from your policy:

  • Emergency access or break-glass accounts to prevent tenant-wide account lockout. In the unlikely scenario all administrators are locked out of your tenant, your emergency-access administrative account can be used to log into the tenant take steps to recover access.
  • Service accounts and service principles, such as the Azure AD Connect Sync Account. Service accounts are non-interactive accounts that are not tied to any particular user. They are normally used by back-end services and allow programmatic access to applications. Service accounts should be excluded since MFA can’t be completed programmatically.
    • If your organization has these accounts in use in scripts or code, consider replacing them with managed identities. As a temporary workaround, you can exclude these specific accounts from the baseline policy.

Application exclusions

Organizations may have many cloud applications in use. Not all of those applications may require equal security. For example, the payroll and attendance applications may require MFA but the cafeteria probably doesn't. Administrators can choose to exclude specific applications from their policy.

Create a Conditional Access policy

The following steps will help create a Conditional Access policy to require those assigned administrative roles to perform multi-factor authentication.

  1. Sign in to the Azure portal as a global administrator, security administrator, or Conditional Access administrator.
  2. Browse to Azure Active Directory > Security > Conditional Access.
  3. Select New policy.
  4. Give your policy a name. We recommend that organizations create a meaningful standard for the names of their policies.
  5. Under Assignments, select Users and groups
    1. Under Include, select All users
    2. Under Exclude, select Users and groups and choose your organization's emergency access or break-glass accounts.
    3. Select Done.
  6. Under Cloud apps or actions > Include, select All cloud apps.
    1. Under Exclude, select any applications that do not require multi-factor authentication.
  7. Under Access controls > Grant, select Grant access, Require multi-factor authentication, and select Select.
  8. Confirm your settings and set Enable policy to On.
  9. Select Create to create to enable your policy.

Next steps

Conditional Access common policies

Simulate sign in behavior using the Conditional Access What If tool