Feature: #93526 - Multi-Factor Authentication

See Issue #93526

Description

TYPO3 is now capable of authentication via multiple factors, in short “multi-factor authentication” or “MFA”. This is sometimes also referred to “2FA” as a 2-Factor Authentication process, where - in order to log in - the user needs

  1. “something you know” (= the password) and
  2. “something you own” (= an authenticator device, or an authenticator app on mobile phones or desktop devices).

Read more about the concepts of MFA on Wikipedia.

TYPO3 ships with some built-in MFA providers by default. But more importantly, TYPO3 now provides an API to allow extension authors to integrate their own MFA providers.

The API is designed in a way to allow providers to be used for TYPO3 Backend Authentication or Frontend Authentication with a multi-factor step in-between.

TYPO3 Core currently provides the integration for the TYPO3 Backend, but will fully support multi-factor authentication for the Frontend in future releases.

Impact

Managing MFA providers is currently accessible via the User Settings module in the new tab called “Account security”, which was previously called just “Password”. The Account security tab displays the current state, if MFA can be configured or is already activated.

By default, the new field is displayed for every backend user. It is possible to disable it for specific users via userTSconfig:

setup.fields.mfaProviders.disabled = 1

Included MFA providers

TYPO3 Core includes two MFA providers:

  1. Time-based one-time password (TOTP)

The most common MFA implementation. A QR-code is scanned (or alternatively, a shared secret can be entered) to connect an Authenticator app such as Google Authenticator, Microsoft Authenticator, 1Password, Authly or others to the system and then synchronize a token, which changes every 30 seconds.

On each log-in, after successfully entering the password, the six-digit code shown by the Authenticator App must be entered.

  1. Recovery codes

This is a special provider which can only be activated if at least one other provider is active, as it’s only meant as a fallback provider, in case the authentication credentials for the “main” provider(s) are lost. It is encouraged to activate this provider, and keep the codes at a safe place.

Setting up MFA for a backend user

Each provider is displayed with its icon, the name and a short description in the MFA configuration module. In case a provider is active this is indicated by a corresponding label, next to the providers’ title. The same goes for a locked provider - an active provider, which can currently not be used since the provider specific implementation detected some unusual behaviour, e.g. to many false authentication attempts. Furthermore does the configured default provider indicate this state with a “star” icon, next to the providers title.

Each inactive provider contains a “Setup” button which opens the corresponding configuration view. This view can be different depending on the MFA provider.

Each active provider contains an “Edit / Change” button, which allows to adjust the providers’ settings. This view allows for example to set a provider as the default (primary) provider, to be used on authentication. Note that the default provider setting will be automatically applied on activation of the first provider or in case it is the recommended provider for this user.

In case the provider is locked, the “Edit / Change” button changes its button title to “Unlock”. This button can therefore be used to unlock the provider. This, depending on the provider to unlock, may require further actions by the user.

The “Deactivate” button can be used to deactivate the provider. This will, depending on the provider, usually also completely remove all provider specific settings.

Another view is the “Authentication view”, which is displayed as soon as a user with at least one active provider has successfully passed the username and password mask.

As for the other views, it is up to the specific provider, used for the current multi-factor authentication attempt, what content is displayed in this view. In any case, if the user has further active providers, the view displays them as “Alternative providers” in the footer. So the user can switch between all activated providers on every authentication attempt.

All providers need to define a locking functionality. In case of the TOTP and recovery code providers, this e.g. includes an attempts count. Therefore, these providers are locked in case a wrong OTP was entered three times in a row. The attempts count is automatically reset as soon as a correct OTP is entered or the user unlocks the provider in the backend.

All Core providers also feature the “Last used” and “Last updated” information which can be retrieved in the “Edit / Change” view.

Administration of users’ MFA providers

If a user is not able to access the backend anymore, e.g. because all of their active providers are locked, MFA needs to be disabled by an administrator for this specific user.

Administrators are able to manage users’ MFA providers in the corresponding user record. The new Multi-factor authentication field displays a list of active providers and a button to deactivate MFA for the user, or only a specific MFA provider.

Note that all of these deactivate buttons are executed immediately, after confirming the appearing dialog, and can’t be undone.

The backend users listing in the backend user module also displays whether MFA is enabled or currently locked, for each user. This allows an administrator a quick glance of the MFA usage of their users.

Via the System => Configuration admin module, it’s possible to get an overview of all currently registered providers in the installation. This is especially helpful to find out the exact provider identifier, needed for some userTSconfig options.

Configuration

Enforcing MFA for users

It seems reasonable to require MFA for specific users or user groups. This can be achieved with $GLOBALS['TYPO3_CONF_VARS']['BE']['requireMfa'] which allows 5 options:

  • 0: Do not require multi-factor authentication (default)
  • 1: Require multi-factor authentication for all users
  • 2: Require multi-factor authentication only for non-admin users
  • 3: Require multi-factor authentication only for admin users
  • 4: Require multi-factor authentication only for system maintainers

To set this requirement only for a specific user or user group, a new userTSconfig option auth.mfa.required is introduced. The userTSconfig option overrules the global configuration.

auth.mfa.required = 1

Note

As soon as MFA is required, the corresponding user is no longer able to access the backend, until at least one MFA provider is activated. After the users’ primary authentication details (e.g. username+password) were successfully validated, a redirect to a dedicated endpoint is performed. On this endpoint, the user can choose and set up one of the available MFA providers. It’s therefore also important for administrators to check if users, which are required to set up MFA, are allowed to choose at least one provider. Have a look at the next section about configuring “allowed providers”.

Allowed provider

It is possible to only allow a subset of the available providers for some users or user groups.

A new configuration option “Allowed multi-factor authentication providers” is available in the user groups record in the “Access List” tab.

There may surely be use cases in which just a single provider should be disallowed for a specific user, which is however configured to be allowed in one of the assigned user groups. Therefore, the new userTSconfig option auth.mfa.disableProviders can be used. It overrules the configuration from the “Access List”, which means if a provider is allowed in “Access List” but disallowed via userTSconfig, it will be disallowed for the user or user group the TSconfig applies to. This does not affect the remaining allowed providers from the “Access List”.

auth.mfa.disableProviders := addToList(totp)

Recommended provider

To recommend a specific provider, $GLOBALS['TYPO3_CONF_VARS]['BE]['recommendedMfaProvider'] can be used and is set to totp (Time-based one-time password) by default.

To set a recommended provider on a per user or user group basis, the new userTSconfig option auth.mfa.recommendedProvider can be used, which overrules the global configuration.

auth.mfa.recommendedProvider = totp

TYPO3 Integration and API

Important

The MFA API is still experimental and subject to change until v11 LTS, since we are looking forward to receive feedback, especially for custom use-cases, the API is not capable yet.

To register a custom MFA provider, the provider class has to implement the new MfaProviderInterface, shipped via a third-party extension. The provider then has to be configured in the extensions’ Services.yaml or Services.php file with the mfa.provider tag.

Vender\Extension\Authentication\Mfa\MyProvider:
   tags:
      - name: mfa.provider
        identifier: 'my-provider'
        title: 'LLL:EXT:extension/Resources/Private/Language/locallang.xlf:myProvider.title'
        description: 'LLL:EXT:extension/Resources/Private/Language/locallang.xlf:myProvider.description'
        setupInstructions: 'LLL:EXT:extension/Resources/Private/Language/locallang.xlf:myProvider.setupInstructions'
        icon: 'tx-extension-provider-icon'

This will register the provider MyProvider with the my-provider identifier. To change the position of your provider the before and after arguments can be useful. This can be needed if you e.g. like your provider to show up prior to any other provider in the MFA configuration module. The ordering is also taken into account in the authentication step while logging in. Note that the user defined default provider will always take precedence.

If you don’t want your provider to be selectable as a default provider, set the defaultProviderAllowed argument to false.

You can also completely deactivate existing providers with:

TYPO3\CMS\Core\Authentication\Mfa\Provider\TotpProvider: ~

The MfaProviderInterface contains a lot of methods to be implemented by the providers. This can be split up into state-providing ones, e.g. isActive or isLocked and functional ones, e.g. activate or update.

Their exact task is explained in the corresponding PHPDoc of the Interface files and the Core MFA provider implementations.

All of these methods are receiving either the current PSR-7 Request object, the MfaProviderPropertyManager or both. The MfaProviderPropertyManager can be used to retrieve and update the provider specific properties and also contains the getUser method, providing the current user object.

To store provider specific data, the MFA API uses a new database field mfa, which can be freely used by the providers. The field contains a JSON encoded Array with each provider as array key. Common properties of such provider array could be active or lastUsed. Since the information is stored in either the be_users or the fe_users table, the context is implicit. Same goes for the user the providers deal with. It is important to have such a generic field so providers are able to store arbitrary data TYPO3 does not need to know about.

To retrieve and update the providers data, the already mentioned MfaProviderPropertyManager, which is automatically passed to all necessary provider methods, should be used. It is highly discouraged to directly access the mfa database field.