Common Conditional Access policy: 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 an MFA policy for your environment.

User exclusions

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

• 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 to take steps to recover access.
  • More information can be found in the article, Manage emergency access accounts in Azure AD.
• Service accounts and service principals, such as the Azure AD Connect Sync Account. Service accounts are non-interactive accounts that aren't tied to any particular user. They're normally used by back-end services allowing programmatic access to applications, but are also used to sign in to systems for administrative purposes. Service accounts like these should be excluded since MFA can't be completed programmatically. Calls made by service principals aren't blocked by Conditional Access.
  • 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.

Subscription activation

Organizations that use Subscription Activation to enable users to “step-up” from one version of Windows to another, may want to exclude the Universal Store Service APIs and Web Application, AppID 45a330b1-b1ec-4cc1-9161-9f03992aa49f from their all users all cloud apps MFA policy.

Template deployment

Organizations can choose to deploy this policy using the steps outlined below or using the Conditional Access templates (Preview).

Create a Conditional Access policy

The following steps will help create a Conditional Access policy to require all users do multifactor authentication.

1. Sign in to the Azure portal as a Conditional Access Administrator, Security Administrator, or Global 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 or workload identities.
   1. Under Include, select All users
   2. Under Exclude, select Users and groups and choose your organization's emergency access or break-glass accounts.
6. Under Cloud apps or actions > Include, select All cloud apps.
   1. Under Exclude, select any applications that don't require multifactor authentication.
7. Under Access controls > Grant, select Grant access, Require multifactor authentication, and select Select.
8. Confirm your settings and set Enable policy to Report-only.
9. Select Create to create to enable your policy.

After confirming your settings using report-only mode, an administrator can move the Enable policy toggle from Report-only to On.

Named locations

Organizations may choose to incorporate known network locations known as Named locations to their Conditional Access policies. These named locations may include trusted IPv4 networks like those for a main office location. For more information about configuring named locations, see the article What is the location condition in Azure Active Directory Conditional Access?

In the example policy above, an organization may choose to not require multifactor authentication if accessing a cloud app from their corporate network. In this case they could add the following configuration to the policy:

1. Under Assignments, select Conditions > Locations.
   1. Configure Yes.
   2. Include Any location.
   3. Exclude All trusted locations.
   4. Select Done.
2. Select Done.
3. Save your policy changes.

Next steps

Conditional Access common policies

Simulate sign in behavior using the Conditional Access What If tool