Auth0 MFA Guide

Add Multi-Factor Authentication to protect user accounts and require additional verification for sensitive operations.

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Overview

What is MFA?

Multi-Factor Authentication (MFA) requires users to provide two or more verification factors to access their accounts. Auth0 supports multiple MFA factors and enables step-up authentication for sensitive operations.

When to Use This Skill

• Adding MFA to protect user accounts
• Requiring additional verification for sensitive actions (payments, settings changes)
• Implementing adaptive/risk-based authentication
• Meeting compliance requirements (PCI-DSS, SOC2, HIPAA)

MFA Factors Supported

Factor	Type	Description
TOTP	Something you have	Time-based one-time passwords (Google Authenticator, Authy)
SMS	Something you have	One-time codes via text message
Email	Something you have	One-time codes via email
Push	Something you have	Push notifications via Auth0 Guardian app
WebAuthn	Something you have/are	Security keys, biometrics, passkeys
Voice	Something you have	One-time codes via phone call
Recovery Code	Backup	One-time use recovery codes

Key Concepts

Concept	Description
acr_values	Request MFA during authentication
amr claim	Authentication Methods Reference - indicates how user authenticated
Step-up auth	Require MFA for specific actions after initial login
Adaptive MFA	Conditionally require MFA based on risk signals

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Step 1: Enable MFA in Tenant

Via Auth0 Dashboard

1. Go to Security → Multi-factor Auth
2. Enable desired factors (TOTP, SMS, etc.)
3. Configure Policies:
   • Always - Require MFA for all logins
   • Adaptive - Risk-based MFA
   • Never - Disable MFA (use step-up instead)

Via Auth0 CLI

# View current MFA configuration
auth0 api get "guardian/factors"

# Enable TOTP (One-time Password)
auth0 api put "guardian/factors/otp" --data '{"enabled": true}'

# Enable SMS
auth0 api put "guardian/factors/sms" --data '{"enabled": true}'

# Enable Push notifications
auth0 api put "guardian/factors/push-notification" --data '{"enabled": true}'

# Enable WebAuthn (Roaming - Security Keys)
auth0 api put "guardian/factors/webauthn-roaming" --data '{"enabled": true}'

# Enable WebAuthn (Platform - Biometrics)
auth0 api put "guardian/factors/webauthn-platform" --data '{"enabled": true}'

# Enable Email
auth0 api put "guardian/factors/email" --data '{"enabled": true}'

Configure MFA Policy

# Set MFA policy: "all-applications" or "confidence-score"
auth0 api patch "guardian/policies" --data '["all-applications"]'

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Step 2: Implement Step-Up Authentication

Step-up auth requires MFA for sensitive operations without requiring it for every login.

The acr_values Parameter

Request MFA by including acr_values in your authorization request:

acr_values=http://schemas.openid.net/pape/policies/2007/06/multi-factor

Implementation Pattern

The general pattern for all frameworks:

1. Check if user has already completed MFA (inspect amr claim)
2. If not, request MFA via acr_values parameter
3. Proceed with sensitive action once MFA is verified

For complete framework-specific examples, see Examples Guide:

• React (basic and custom hook)
• Next.js (App Router)
• Vue.js
• Angular

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Additional Resources

This skill is split into multiple files for better organization:

Step-Up Examples

Complete code examples for all frameworks:

• React (basic and custom hook patterns)
• Next.js (App Router with API routes)
• Vue.js (composition API)
• Angular (services and components)

Backend Validation

Learn how to validate MFA status on your backend:

• Node.js / Express JWT validation
• Python / Flask validation
• Middleware examples

Advanced Topics

Advanced MFA implementation patterns:

• Adaptive MFA with Auth0 Actions
• Conditional MFA based on risk signals
• MFA Enrollment API

Reference Guide

Common patterns and troubleshooting:

• Remember MFA for 30 days
• MFA for high-value transactions
• MFA status display
• Error handling
• AMR claim values
• Testing strategies
• Security considerations

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Related Skills

• auth0-quickstart - Basic Auth0 setup
• auth0-passkeys - WebAuthn/passkey implementation
• auth0-actions - Custom authentication logic

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References

• Auth0 MFA Documentation
• Step-Up Authentication
• MFA API
• acr_values Parameter