How to Implement MFA for All Users in Entra ID

Michael Abboud

Passwords alone aren’t enough anymore. Phishing, credential stuffing, and password reuse attacks are rampant, and a single stolen password can open the door to your entire tenant. Multi-Factor Authentication (MFA) adds a critical extra layer, blocking over 99% of credential-based attacks. Making MFA universal ensures attackers can’t rely on the weakest link.

The Risk If Ignored

  • Stolen passwords = instant access: Attackers can compromise accounts with no challenge.

  • Tenant-wide risk: One breached account can be used to spread malware or steal data.

  • Compliance failure: Many regulations mandate MFA as a baseline control.

How to Implement

  1. Go to Entra ID Admin Center.

  2. Navigate: Security > Conditional Access.

  3. Create a new policy:

    • Assignments: Target all users.

    • Cloud apps: Select all apps.

    • Access controls: Require Multi-Factor Authentication.

  4. Exclude only break-glass accounts (secured with long, complex passwords and monitored closely).

  5. Enable and enforce the policy.

Commonly Overlooked Pitfalls

  • Partial rollout: If MFA isn’t required for all apps, attackers will find the unprotected ones.

  • Over reliance on SMS: Text-based MFA can still be phished or SIM-swapped—push or app-based methods are stronger.

  • Forgotten service accounts: Some scripts or legacy apps can break when MFA is enforced; these should be updated or isolated.

Steps to Strengthen Protection

  1. Promote stronger MFA methods

    • Encourage users to use authenticator apps or FIDO2 keys instead of SMS codes.

  2. Enable MFA registration policy

    • Require users to register methods during onboarding to avoid gaps.

  3. Audit MFA coverage

    • Check Entra ID > Sign-in logs to ensure MFA challenges are being applied consistently.

  4. Pair with Conditional Access for risky sign-ins

    • Add risk-based controls to challenge unusual login attempts more aggressively.

Implementing MFA for all users is one of the simplest and most effective defenses against modern attacks. With a single policy, you shut down credential-based threats before they begin. Universal MFA isn’t optional anymore, it's the baseline for any secure tenant.

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