auth0-mfa

SKILL.md

Auth0 MFA Guide

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

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

Step 1: Enable MFA in Tenant

Via Auth0 Dashboard

Go to Security → Multi-factor Auth

Enable desired factors (TOTP, SMS, etc.)

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"]'

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:

Check if user has already completed MFA (inspect amr claim)

If not, request MFA via acr_values parameter

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

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

Related Skills

auth0-quickstart - Basic Auth0 setup

auth0-passkeys - WebAuthn/passkey implementation

auth0-actions - Custom authentication logic

References

Auth0 MFA Documentation

Step-Up Authentication

MFA API

acr_values Parameter

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