Traditionally when using External login providers (OAuth), a backoffice user or website member will need to exist first and then that user can link their user account to an external login provider in the backoffice or edit profile page.

In many cases, however, the external login provider you install will be the source of truth for all of your users.

In this case, you will want to provide a Single Sign On (SSO) approach to logging in. This would enable the creating of user accounts on the external login provider and then automatically give them access to Umbraco. This is called auto-Linking.

Configure External Login provider

To enable auto linking you have to implement a custom named configuration of BackOfficeExternalLoginProviderOptions or MemberExternalLoginProviderOptions for users or members, respectively.

Example for users

This example shows connection to an Open ID Connect Service such as IdentityServer4 or OpenIDDict

You can first create a OpenIdConnectBackOfficeExternalLoginProviderOptions.cs file which configures the options like

using Microsoft.Extensions.Options;
using Umbraco.Cms.Core;
using Umbraco.Cms.Web.BackOffice.Security;

namespace Umbraco9
{
    public class OpenIdConnectBackOfficeExternalLoginProviderOptions : IConfigureNamedOptions<BackOfficeExternalLoginProviderOptions>
    {
        public const string SchemeName = "OpenIdConnect";
        public void Configure(string name, BackOfficeExternalLoginProviderOptions options)
        {
            if (name != "Umbraco." + SchemeName)
            {
                return;
            }

            Configure(options);
        }

        public void Configure(BackOfficeExternalLoginProviderOptions options)
        {
            options.ButtonStyle = "btn-danger";
            options.Icon = "fa fa-cloud";
            options.AutoLinkOptions = new ExternalSignInAutoLinkOptions(
                // must be true for auto-linking to be enabled
                autoLinkExternalAccount: true,

                // Optionally specify default user group, else
                // assign in the OnAutoLinking callback
                // (default is editor)
                defaultUserGroups: new[] { Constants.Security.EditorGroupAlias },

                // Optionally specify the default culture to create
                // the user as. If null it will use the default
                // culture defined in the web.config, or it can
                // be dynamically assigned in the OnAutoLinking
                // callback.

                defaultCulture: null,
                // Optionally you can disable the ability to link/unlink
                // manually from within the back office. Set this to false
                // if you don't want the user to unlink from this external
                // provider.
                allowManualLinking: false
            )
            {
                // Optional callback
                OnAutoLinking = (autoLinkUser, loginInfo) =>
                {
                    // You can customize the user before it's linked.
                    // i.e. Modify the user's groups based on the Claims returned
                    // in the externalLogin info
                },
                OnExternalLogin = (user, loginInfo) =>
                {
                    // You can customize the user before it's saved whenever they have
                    // logged in with the external provider.
                    // i.e. Sync the user's name based on the Claims returned
                    // in the externalLogin info

                    return true; //returns a boolean indicating if sign in should continue or not.
                }
            };

            // Optionally you can disable the ability for users
            // to login with a username/password. If this is set
            // to true, it will disable username/password login
            // even if there are other external login providers installed.
            options.DenyLocalLogin = false;

            // Optionally choose to automatically redirect to the
            // external login provider so the user doesn't have
            // to click the login button. This is
            options.AutoRedirectLoginToExternalProvider = false;
        }
    }
}

Additionally, there are more advanced properties for BackOfficeExternalLoginProviderOptions:

• BackOfficeExternalLoginProviderOptions.CustomBackOfficeView

  • Allows for specifying a custom angular HTML view that will render in place of the default external login button. The purpose of this is in case you want to completely change the UI but also in these circumstances:

    • You want to display something different where external login providers are listed: in the login screen vs the backoffice panel vs on the logged-out screen. This same view will render in all of these cases but you can use the current route parameters to customize what is shown.

    • You want to change how the button interacts with the external login provider. For example, instead of having the site redirect on button-click, you want to open a popup window to load the external login provider.

  • The path is a virtual path, for example: "~/App_Plugins/MyPlugin/BackOffice/my-external-login.html"

  • When specifying this view it is 100% up to your angular view and affiliated angular controller to perform all required logic.

To register this configuration class, you can call the following from your startup.cs:

services.ConfigureOptions<OpenIdConnectBackOfficeExternalLoginProviderOptions>();

We recommend to create an extension method on the IUmbracoBuilder, to add the Open Id Connect Authentication, like this This extension can also handle the configuration of OpenIdConnectBackOfficeExternalLoginProviderOptions:

public static IUmbracoBuilder AddOpenIdConnectAuthentication(this IUmbracoBuilder builder)
{
    // Register OpenIdConnectBackOfficeExternalLoginProviderOptions here rather than require it in startup
    builder.Services.ConfigureOptions<OpenIdConnectBackOfficeExternalLoginProviderOptions>();

    builder.AddBackOfficeExternalLogins(logins =>
    {
        logins.AddBackOfficeLogin(
            backOfficeAuthenticationBuilder =>
            {
                backOfficeAuthenticationBuilder.AddOpenIdConnect(
                    // The scheme must be set with this method to work for the back office
                    backOfficeAuthenticationBuilder.SchemeForBackOffice(OpenIdConnectBackOfficeExternalLoginProviderOptions.SchemeName),
                    options =>
                    {
                        // use cookies
                        options.SignInScheme = CookieAuthenticationDefaults.AuthenticationScheme;
                        // pass configured options along
                        options.Authority = "https://localhost:5000";
                        options.ClientId = "YOURCLIENTID";
                        options.ClientSecret = "YOURCLIENTSECRET";
                        // Use the authorization code flow
                        options.ResponseType = OpenIdConnectResponseType.Code;
                        options.AuthenticationMethod = OpenIdConnectRedirectBehavior.RedirectGet;
                        // map claims
                        options.TokenValidationParameters.NameClaimType = "name";
                        options.TokenValidationParameters.RoleClaimType = "role";


                        options.RequireHttpsMetadata = true;
                        options.GetClaimsFromUserInfoEndpoint = true;
                        options.SaveTokens = true;
                        // add scopes
                        options.Scope.Add("openid");
                        options.Scope.Add("email");
                        options.Scope.Add("roles");
                        options.UsePkce = true;
                    });
            });
    });
    return builder;
}

Finally this extension can also be called from the Startup.cs like the example below:

services.AddUmbraco(_env, _config)
   .AddBackOffice()
   .AddWebsite()
   .AddComposers()
   .AddOpenIdConnectAuthentication()
   .Build();

Example for members

The way to implement auto linking for members is fairly similar to how it is for users. The main difference is the UI, where Umbraco do not have a fixed login page for members. Instead, Umbraco ships with some Partial Macro Snippets for Login and EditProfile that contains handling of Login and manual linking of the configured external member providers.

When auto-linking is enabled, only the Login snippet is relevant as users do not have to register before.

The following example will show how to use Google and external login provider. You can first create a GoogleMemberExternalLoginProviderOptions.cs file which configures the options like

using System;
using Microsoft.Extensions.Options;
using Umbraco.Cms.Core;
using Umbraco.Cms.Web.BackOffice.Security;

namespace Umbraco9
{
    public class GoogleMemberExternalLoginProviderOptions : IConfigureNamedOptions<MemberExternalLoginProviderOptions>
    {
        public const string SchemeName = "Google";

        public void Configure(string name, MemberExternalLoginProviderOptions options)
        {
            if (name != Constants.Security.MemberExternalAuthenticationTypePrefix + SchemeName)
            {
                return;
            }

            Configure(options);
        }

        public void Configure(MemberExternalLoginProviderOptions options) =>
            options.AutoLinkOptions = new MemberExternalSignInAutoLinkOptions(
                // Must be true for auto-linking to be enabled
                autoLinkExternalAccount: true,

                // Optionally specify the default culture to create
                // the user as. If null it will use the default
                // culture defined in the web.config, or it can
                // be dynamically assigned in the OnAutoLinking
                // callback.
                defaultCulture: null,

                // Optionally specify the default "IsApprove" status. Must be true for auto-linking.
                defaultIsApproved:true,

                // Optionally specify the member type alias. Default is "Member"
                defaultMemberTypeAlias:"Member",

                // Optionally specify the member groups names to add the auto-linking user to.
                defaultMemberGroups: Array.Empty<string>()
            )
            {
                // Optional callback
                OnAutoLinking = (autoLinkUser, loginInfo) =>
                {
                    // You can customize the member before it's linked.
                    // i.e. Modify the member's groups based on the Claims returned
                    // in the externalLogin info
                },
                OnExternalLogin = (user, loginInfo) =>
                {
                    // You can customize the member before it's saved whenever they have
                    // logged in with the external provider.
                    // i.e. Sync the member's name based on the Claims returned
                    // in the externalLogin info

                    return true; //returns a boolean indicating if sign in should continue or not.
                }
            };
    }
}

To register this configuration class, you can call the following from your startup.cs:

services.ConfigureOptions<GoogleMemberExternalLoginProviderOptions>();

Like for users, we recommend creating an extension method on the IUmbracoBuilder, to add the Google Authentication, like this. This extension can also handle the configuration of GoogleMemberExternalLoginProviderOptions:

public static IUmbracoBuilder AddMemberGoogleAuthentication(this IUmbracoBuilder builder)
{
    // Register GoogleMemberExternalLoginProviderOptions here rather than require it in startup
    builder.Services.ConfigureOptions<GoogleMemberExternalLoginProviderOptions>();

    builder.AddMemberExternalLogins(logins =>
    {
        logins.AddMemberLogin(
            memberAuthenticationBuilder =>
            {
                memberAuthenticationBuilder.AddGoogle(
                    // The scheme must be set with this method to work for the Umbraco members
                    memberAuthenticationBuilder.SchemeForMembers(GoogleMemberExternalLoginProviderOptions.SchemeName),
                    options =>
                    {
                        options.ClientId = "YOURCLIENTID";
                        options.ClientSecret = "YOURCLIENTSECRET";
                    });
            });
    });
    return builder;
}

Finally this extension can also be called from the Startup.cs like the example below:

services.AddUmbraco(_env, _config)
   .AddBackOffice()
   .AddWebsite()
   .AddComposers()
   .AddMemberGoogleAuthentication()
   .Build();

Local logins

If you have configured auto-linking, then any auto-linked user or member will have an empty password assigned and they will not be able to log in locally (via username and password). In order to log in locally, they will have to assign a password to their account in the backoffice or the edit profile page.

For users only, if the DenyLocalLogin option is enabled, then all password changing functionality in the backoffice is also disabled and local login is not possible.

Transfering Claims from External identities

In some cases you may want to flow a Claim returned in your external login provider to the Umbraco backoffice identity's Claims (the authentication cookie). This can be done during the OnAutoLinking and OnExternalLogin.

Reason for this could be to store the external login provider user ID into the backoffice identity cookie. That way it can be retrieved on each request in order to look up some data in another system that needs the current user id from the external login provider.

Example

This is a very simplistic example for brevity, no null checks, etc...

OnAutoLinking = (user, loginInfo) => {
    // You can customize the user before it's linked.
    // i.e. Modify the user's groups based on the Claims returned
    // in the externalLogin info
    var extClaim = externalLogin
        .Principal
        .FindFirst("MyClaim");
    user.Claims.Add(new IdentityUserClaim<string>
    {
        ClaimType = extClaim.Type,
        ClaimValue = extClaim.Value,
        UserId = user.Id
    });
},
OnExternalLogin = (user, loginInfo) => {
    // You can customize the user before it's saved whenever they have
    // logged in with the external provider.
    // i.e. Sync the user's name based on the Claims returned
    // in the externalLogin info
    var extClaim = externalLogin
        .Principal
        .FindFirst("MyClaim");
    user.Claims.Add(new IdentityUserClaim<string>
    {
        ClaimType = extClaim.Type,
        ClaimValue = extClaim.Value,
        UserId = user.Id
    });
    return true;
}

Storing external login provider data

In some cases, you may need to persist data from your external login provider like Access Tokens, etc. You can persist this data to the affiliated user's external login data via the IExternalLoginWithKeyService. The void Save(Guid userOrMemberKey,IEnumerable<IExternalLoginToken> tokens) overload takes a new model of type IEnumerable<IExternalLogin>. IExternalLogin contains a property called UserData. This is a blob text column so can store any arbitrary data for the external login provider.

Having the ability to replace the logic to validate a username and password against a custom data store is important to some developers. Normally in ASP.Net Core Identity this would require you to override the UmbracoBackOfficeUserManager.CheckPasswordAsync implementation and then replace the UmbracoBackOfficeUserManager with your own class during startup. Since this is a common task we've made this process a lot easier with an interface called IBackOfficeUserPasswordChecker.

Here are the steps to specify your own logic for validating a username and password for the backoffice:

1. Create an implementation of Umbraco.Cms.Core.Security.IBackOfficeUserPasswordChecker

   • There is one method in this interface: Task<BackOfficeUserPasswordCheckerResult> CheckPasswordAsync(BackOfficeIdentityUser user, string password);

   • The result of this method can be 3 things:

     • ValidCredentials = The credentials entered are valid and the authorization should proceed

     • InvalidCredentials = The credentials entered are not valid and the authorization process should return an error

     • FallbackToDefaultChecker = This is an optional result which can be used to fallback to Umbraco's default authorization process if the credentials could not be verified by your own custom implementation

   For example, to always allow login when the user enters the password test you could do:

   Copy

   using System.Threading.Tasks;
   using Umbraco.Core.Models.Identity;
   using Umbraco.Core.Security;
   
   namespace MyNamespace
   {
       public class MyPasswordChecker : IBackOfficeUserPasswordChecker
       {
           public Task<BackOfficeUserPasswordCheckerResult> CheckPasswordAsync(BackOfficeIdentityUser user, string password)
           {
               var result = (password == "test")
                   ? Task.FromResult(BackOfficeUserPasswordCheckerResult.ValidCredentials)
                   : Task.FromResult(BackOfficeUserPasswordCheckerResult.InvalidCredentials);
   
               return result;
           }
       }
   }

2. Register the MyPasswordChecker in your Startup.ConfigureServices method:

   Copy

   public void ConfigureServices(IServiceCollection services)
   {
       ...
   
       services.AddUnique<IBackOfficeUserPasswordChecker, MyPasswordChecker>();
   }

The BackOfficeUserManager is the ASP.NET Core Identity UserManager implementation in Umbraco. It exposes APIs for working with Umbraco Users via the ASP.NET Core Identity including password handling.

Extending

The BackOfficeUserManager can be replaced during startup in order to use your own implementation. This may be required if you want to extend the functionality of the BackOfficeUserManager for things like supporting two-factor authentication(2FA).

Example

You can replace the BackOfficeUserManager in the startup class by using the SetBackOfficeUserManager extension on the IUmbracoBuilder.

public class Startup
{
   ...
    public void ConfigureServices(IServiceCollection services)
    {
        services.AddUmbraco(_env, _config)
            .AddBackOffice()
            .AddWebsite()
            .AddComposers()
            .SetBackOfficeUserManager<CustomBackOfficeUserManager>()
            .Build();
    }
  ...
}

You can then implement your custom BackOfficeUserManager, like this. Note the constructor minimum needs to inject what is required for the base BackOfficeUserManager class:

 public class CustomBackOfficeUserManager : BackOfficeUserManager
{
    public CustomBackOfficeUserManager(
        IIpResolver ipResolver,
        IUserStore<BackOfficeIdentityUser> store,
        IOptions<BackOfficeIdentityOptions> optionsAccessor,
        IPasswordHasher<BackOfficeIdentityUser> passwordHasher,
        IEnumerable<IUserValidator<BackOfficeIdentityUser>> userValidators,
        IEnumerable<IPasswordValidator<BackOfficeIdentityUser>> passwordValidators,
        BackOfficeErrorDescriber errors,
        IServiceProvider services,
        IHttpContextAccessor httpContextAccessor,
        ILogger<CustomBackOfficeUserManager> logger,
        IOptions<UserPasswordConfigurationSettings> passwordConfiguration,
        IEventAggregator eventAggregator,
        IBackOfficeUserPasswordChecker backOfficeUserPasswordChecker)
        : base(
            ipResolver,
            store,
            optionsAccessor,
            passwordHasher,
            userValidators,
            passwordValidators,
            errors,
            services,
            httpContextAccessor,
            logger,
            passwordConfiguration,
            eventAggregator,
            backOfficeUserPasswordChecker)
    {
    }

    //Override whatever you need, e.g. SupportsUserTwoFactor.
    public override bool SupportsUserTwoFactor => false;
}

Notifications

There are many notifications you can handle on the BackOfficeUserManager. Internally these are mainly used for auditing but there are some that allow you to customize some workflows:

• SendEmailNotification

  • This is a generic notification but it has a property EmailType that specify the email type. This type can be UserInvite. In that case, it allows you to take control over how a user in the backoffice is invited. This might be handy if you are using an External Login Provider that has the DenyLocalLogin option assigned and you still want to have the user invite functionality available. In this setup, all of your users are controlled by your external login provider so you would need to handle the user invite flow yourself by using this event and inviting the user via your external provider. If you are using this event to replace the default functionality you will need to tell Umbraco that you've handled the invite by calling the SendEmailNotification.HandleEmail() method.)

• UserLogoutSuccessNotification

  • This is specifically used if you have an External Login Provider in use and you want to log out of that external provider when the user is logged out of the backoffice (that is log out of everywhere). The notification has a property SignOutRedirectUrl. If this property is assigned then Umbraco will redirect to that URL upon successful backoffice sign out in order to sign the user out of the external login provider.

There is one default admin user in any Umbraco installation. This is the first user of the system.

Step one: Clear the connection string status in configuration

The first step is to clear the connection string to the database in the configuration. This is done to trigger the installation wizard.

That means that in your appsettings configuration files it should look like this:

{
  "ConnectionStrings": {
    "umbracoDbDSN": ""
  }
}

Step Two: Run the installer

If you now open your browser and surf to the website, you will see that the installer launches. Enter your new details, and use the original connection string. You are good to go.

It's impossible to brute force the authentication on the login screen because after MaxFailedAccessAttemptsBeforeLockout the account of the user will be locked, and until that account is unlocked in the Users section, no attempt will succeed.

Password reset on login screen

When you submit the password reset form, an email is sent to the user with a link. This link contains a random token for this user that is valid for 24 hours.

The settings AllowPasswordReset is documented in the Umbraco Security Settings and e-mail configuration settings in Backoffice Login Password Reset Section

Password reset of a non-existing user

If the user that is specified in the form does not exist, no e-mail will be sent and there will be no response in the form that this user does not exist. This is done to prevent leaking which users have an account.

Password reset of a locked user

If a user is locked out, it is possible to do a password reset. After the e-mail with the password reset link is followed, the user will still be locked out unless the user has specified the new password, in which case the user will automatically be unlocked.

Reset admin user password

If you lost the admin user password and you need to reset it, check this article.

In this article, you will find everything you need regarding security within Umbraco.

The Umbraco Trust Center (external)

On our main website, we have a dedicated security section which provides all the details you need to know about security within the Umbraco CMS. This includes how to report a vulnerability.

SSL/HTTPS

We highly encourage the use of HTTPS on Umbraco websites, especially in production environments. By using HTTPS you greatly improve the security of your website.

In the "Use HTTPS" article you can learn more about how to use HTTPS and how to set it up.

Security Settings

Learn which password settings that can be configured in Umbraco.

Security Hardening

Learn about how to harden the security on your Umbraco website to secure it even further.

Security on Umbraco Cloud

When your project is hosted on Umbraco Cloud, you might be interested in more details about the security of the hosting. This information can be found in the Umbraco Cloud FAQs section of the documentation.

Backoffice users and website members (external)

Authentication for backoffice users and website members in Umbraco uses ASP.NET Core Identity which is a flexible and extendable framework for authentication.

Out of the box Umbraco ships with a custom ASP.NET Core Identity implementation which uses Umbraco's database data. Normally this is fine for most Umbraco developers, but in some cases the authentication process needs to be customized.

External login providers

The Umbraco users and members supports external login providers (OAuth) for performing authentication of your users/members. This could be any OpenIDConnect provider such as Entra ID/Azure Active Directory, Identity Server, Google or Facebook.

Two-factor authentication

The Umbraco members supports a two-factor authentication (2FA) abstraction for implementing a 2FA provider of your choice. This could be any Time-based One-time Password (TOTP) Algorithm, including Microsoft and Google Authenticator Apps

BackOfficeUserManager and Notifications

The BackOfficeUserManager is the ASP.NET Core Identity UserManager implementation in Umbraco. It exposes APIs for working with Umbraco Users via the ASP.NET Core Identity including password handling.

Custom password check

In most cases External login providers (OAuth) will meet the needs of most users when needing to authenticate with external resources but in some cases you may need to only change how the username and password credentials are checked.

This is typically a legacy approach to validating credentials with external resources but it is possible.

You are able to check the username and password against your own credentials store by implementing a IBackOfficeUserPasswordChecker.

Sensitive data on members

Marking fields as sensitive will hide the data in those fields for backoffice users that do not have permission to view personal data of members.

Learn more about this in the Sensitive Data article.

Setup Umbraco for a FIPS Compliant Server

How to configure Umbraco to run on a FIPS compliant server.

Reset admin password

Use this guide to reset the password of the "admin" user.

If you need to reset accounts of every other user while you still have administrative action, check this "reset normal user password" article.

Other articles related to security

• Routing requirements for backoffice authentication

• Health Checks

• Consent Service

Both the Umbraco backoffice users and website members supports external login providers (OAuth) for performing authentication of your users or members. This could be any OpenIDConnect provider such as Entra ID/Azure Active Directory, Identity Server, Google or Facebook.

Unlike previous major releases of Umbraco the use of Identity Extensions package is no longer required.

Install an appropriate nuget package for the provider you wish to use. Some popular ones found in Nuget include:

• Google

• Facebook

• Microsoft

• Twitter

• Open ID Connect

• Others

To configure the provider create a new static extension class for your provider and configure a custom named options like GoogleBackOfficeExternalLoginProviderOptions described in details in the auto linking section. The code example below shows how the configuration for Google Authentication can be done. You can find an example for how this can be done with Microsoft in the Authenticating on the Umbraco backoffice with Active Directory credentials article.

using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Extensions;
using Umbraco.Cms.Web.BackOffice.Security;
using Microsoft.Extensions.DependencyInjection;
using Microsoft.Extensions.Configuration;

namespace Umbraco.Cms.Web.UI.NetCore.Configuration
{
    public static class GoogleBackofficeAuthenticationExtensions
    {
        public static IUmbracoBuilder AddGoogleBackofficeAuthentication(this IUmbracoBuilder builder)
        {
            builder.AddBackOfficeExternalLogins(logins =>
            {
                logins.AddBackOfficeLogin(
                    backOfficeAuthenticationBuilder =>
                    {
                        backOfficeAuthenticationBuilder.AddGoogle(
                            // The scheme must be set with this method to work for the back office
                            backOfficeAuthenticationBuilder.SchemeForBackOffice(GoogleBackOfficeExternalLoginProviderOptions.SchemeName),
                            options =>
                            {
                                //  By default this is '/signin-google' but it needs to be changed to this
                                options.CallbackPath = "/umbraco-google-signin";
                                options.ClientId = "YOURCLIENTID";
                                options.ClientSecret = "YOURCLIENTSECRET";
                            });
                    });
            });
            return builder;
        }
    }
}

And another, but fairly similar, example of configuration for Google Authentication for members may look like:

using Microsoft.Extensions.DependencyInjection;
using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Extensions;

namespace Umbraco.Cms.Web.UI.NetCore.Configuration
{
    public static class GoogleMemberAuthenticationExtensions
    {
        public static IUmbracoBuilder AddGoogleMemberAuthentication(this IUmbracoBuilder builder)
        {
            builder.AddMemberExternalLogins(logins =>
            {
                logins.AddMemberLogin(
                    memberAuthenticationBuilder =>
                    {
                        memberAuthenticationBuilder.AddGoogle(
                            // The scheme must be set with this method to work for the back office
                            memberAuthenticationBuilder.SchemeForMembers(GoogleMemberExternalLoginProviderOptions.SchemeName),
                            options =>
                            {
                                options.ClientId = "YOURCLIENTID";
                                options.ClientSecret = "YOURCLIENTSECRET";
                            });
                    });
            });
            return builder;
        }
    }
}

Finally, update ConfigureServices in your Startup.cs class to register your configuration with Umbraco. An example may look like:

public void ConfigureServices(IServiceCollection services)
{
    services.AddUmbraco(_env, _config)
        .AddBackOffice()
        .AddWebsite()
        .AddComposers()
        .AddGoogleBackofficeAuthentication()
        .AddGoogleMemberAuthentication()
        .Build();
}

For a more in depth article on how to setup OAuth providers in .NET refer to the Microsoft Documentation.

Depending on the provider you've configured and its caption/color, the end result will look similar to this for users:

Because Umbraco do not control the UI of members, this can be setup to look exactly like you would like, but Umbraco ships with partial macro snippets for Login that will show all configured external login providers.

Auto-linking accounts for custom OAuth providers

Traditionally a backoffice user or members will need to exist first and then that user can link their user account to an external login provider in the backoffice. In many cases however, the external login provider you install will be the source of truth for all of your users.

In this case, you would want to be able to create user accounts in your external login provider and then have that user given access to the backoffice without having to create the user in the backoffice first. This is done via auto-linking.

This could also be the case for members if your website allows public creation of members. In this case, the creation process can be simplified by allowing auto-linking the external account. E.g. using Facebook, Twitter or Google.

Read more about auto linking.

The cookies listed in this article are required only for accessing the Backoffice. You can include these in your own cookie policy, if you wish.

Necessary Cookies

The below cookies are necessary for accessing the Umbraco Backoffice and functioning of the website. They allow you to enjoy the contents and services you request.

The UMB_SESSION cookie is secure if you are using HTTPS pages. However, if you wish to secure the cookie in your code, add the following in the Program.cs file after Build();

services.AddSession(options =>
    {
        options.Cookie.Name = "UMB_SESSION";
        options.Cookie.HttpOnly = true;
        options.Cookie.SecurePolicy = CookieSecurePolicy.Always;
    });

For information on the rest of the cookies, see the Constants-Web.cs file on Github.

Here you find some tips and trick for hardening the security of your Umbraco installation.

Lock down access to your Umbraco folder (IIS)

It’s considered a good practice to lock down the Umbraco folder to specific IP addresses and/or IP ranges to ensure this folder is not available to everyone.

The prerequisite of this to work is that you’re using

If you’ve made sure that you’ve installed this on your server we can start locking down our Umbraco folder. This can be down by following these three steps.

1. We are going to lock down /Umbraco/, but because API-controllers and Surface-controller will use the path /umbraco/api/ and /umbraco/surface/ these will also be locked down. Our first rule in the IISRewrite.config will be used to make sure that these are not locked by IP-address.

Some older versions of Umbraco also relied on /umbraco/webservices/ for loadbalancing purposes. If you're loadbalancing you should also add umbraco/webservices to the rule.

1. Get the IP-addresses of your client and write these down like a regular expression. If the IP-addresses are for example 213.3.10.8 and 88.4.43.108 the regular expression would be "213.3.10.8|88.4.43.108".

2. Lock down the Umbraco folder by putting this rule into your IISRewrite-rules

If you now go to /umbraco/ from a different IP-address the login screen will not be rendered.

This tutorial walks through configuring Umbraco and Lucene to be FIPS compliant and serve up websites on a server with FIPS enabled.

What is FIPS?

The Federal Information Processing Standard (FIPS) Publication 140-2, (), is a U.S. government computer security standard used to define approved cryptographic modules. The FIPS 140 standard also sets forth requirements for key generation and for key management.

Microsoft Windows has a "FIPS mode" of operation where it detects the cryptographic algorithms used by software running on it and will throw exceptions if it detects the use of non-FIPS compliant algorithms. Using MD5 hashing is generally the biggest culprit of issues running on FIPS enabled servers.

How can I test my site with FIPS enabled?

FIPS can be enabled through your Local Group Policy, Registry Setting, or Network Adapter setting. For more information about how to enable FIPS mode on Windows see this tutorial:

What version of Umbraco is FIPS compliant?

Umbraco 7.6.4+ has implemented checks for when FIPS mode is enabled on the server that it is installed on. When FIPS mode is detected, the cryptographic algorithms for hashing are changed to a FIPS compliant algorithm. When FIPS mode is disabled, then Umbraco uses backward compatible algorithms (MD5) so as not to affect existing installs. As of Umbraco version 7.6.4, the FIPS compliant cryptographic algorithm used is SHA1.

Umbraco 9.0.0 and key dependencies are FIPS compliant

Since Umbraco 9, the dependency to Lucene.NET is updated to version 4+. Thereby are both Umbraco and all key dependencies FIPS compliant.

FAQ

Can I install Umbraco directly on a version of Windows with FIPS mode enabled?

Installing to the FIPS server may not work. It's best to deploy an existing known working version to the FIPS server.

Password settings

The settings for Umbraco passwords are configurable in appsettings. There are two different configuration objects - One for Umbraco Members and one for Users.

For more information see the .

Password reset settings

Umbraco backend users can , or if they try too much, have a locked out account.

To deactivate the User password reset look at the section.

To configure password reset verify the section.

Other security settings

• If set to false this can be used to try to render pages in a way that they are not supposed to

• If set to false this can be used to do an enumeration of the nodes in your website and find hidden pages.

• Umbraco Forms: and DisableFormCaching

We highly encourage the use of HTTPS on Umbraco websites especially in production environments. By using HTTPS you greatly improve the security of your website.

There are several benefits of HTTPS:

• Trust - when your site is delivered over HTTPS your users will see that your site is secured, they are able to view the certificate assigned to your site and know that your site is legitimate

• Removing an attack vector called (or network Sniffing)

• Guards against , an attacker will have a hard time obtaining an authentic SSL certificate

• Google likes HTTPS, it may help your site's rankings

Another benefits of HTTPS is that you are able to use the protocol if your web server and browser support it.

Set UseHttps configuration option

Umbraco allows you to force HTTPS for all backoffice communications by using the following configuration:

In Umbraco 9, set the UseHttps key in appSettings to true.

This options does several things when it is turned on:

• All non-https requests to any backoffice controller is redirected to https

• All self delivered Umbraco requests (i.e. scheduled publishing, keep alive, etc...) are performed over https

• All Umbraco notification emails with links generated have https links

• All authorization attempts for backoffice handlers and services will be denied if the request is not over https

Redirect traffic in code

The .NET5+ way to handle this, is by adding this HttpsRedirectionMiddleware to your pipeline in Startup.cs. This can be done by adding app.UseHttpsRedirection(); before the call to app.UseUmbraco() in the Configure method:

Redirect traffic on IIS

Once you enable HTTPS for your site you should redirect all requests to your site to HTTPS, this can be done with an IIS rewrite rule. The IIS rewrite module needs to be installed for this to work, most hosting providers will have that enabled by default.

In your web.config find or add the <system.webServer><rewrite><rules> section and put the following rule in there. This rule will redirect all requests for the site http://mysite.com URL to the secure https://mysite.com URL and respond with a permanent redirect status.

SSL versus TLS

While the deprecated SSL (2.0 and 3.0) are not supported anymore by modern browsers, some of the Umbraco configuration still uses SSL. But rest assured, that is only the name.

Marking fields and properties on member data as sensitive will hide the data in those fields for backoffice users that are not privy to the data.

In this article, you will get an overview of how you can grant and/or deny your users access to sensitive data as well as how to mark data as sensitive.

Grant or deny access to sensitive data

Every new Umbraco installation ships with a default set of User Groups. One of them is the Sensitive data User Group. To give users in the backoffice access to view and work with sensitive data, they need to be part of the Sensitive data User Group.

Any users who are not part of the Sensitive data User Group, will not be able to see the data in the properties that are marked as sensitive. Instead, they will see a generic message: "This value is hidden. If you need access to view this value please contact your website administrator."

While not part of the Sensitive data User Group it is also not possible to export members or member data.

Follow these steps in order to grant a user access to sensitive data:

• Navigate to the Users section in the Umbraco backoffice.

• Ensure that Users is selected from the Users tree.

• Select the Groups menu in the top-right corner.

• Choose the Sensitive data group.

• Click Add in the Users box on the right.

• Select the users you want to give access to the sensitive data.

• Click Submit.

• Save the User Group.

The users you have added to the Sensitive data User Group will now be able to:

• See member data that has been marked as sensitive,

• Mark data and properties on Member Types as sensitive, and

• Export members and member data.

Marking data as sensitive

Once your user is added to the Sensitive data User Group, you have access to add and configure member properties containing sensitive data.

• Navigate to the Settings section in the Umbraco backoffice.

• Open the Member Types in the Settings tree.

• Select the Member Type you wish to edit.

• Add a property or configure an existing property.

• Locate the Is sensitive data option at the bottom of the Property settings dialog.

• Click to enable.

• Click Submit to update the property configuration.

• Click Save to save the changes on the Member Type.

When the Is sensitive data option is enabled, the value and data in the property will only be visible to the users with access to sensitive data.

Sometimes it might be necessary to validate the contents of a file before it gets saved to disk when uploading trough the backoffice.

To help with this, Umbraco supplies a FileStreamSecurityValidator that runs all registered IFileStreamSecurityAnalyzer implementations on the file streams it receives from it's different file upload endpoints. When any of the analyzers deem the file to be unsafe, the endpoint disregards the file and shows a relevant validation message where appropriate. This all happens in memory before the stream is written to a temporary file location.

Implementing a FileStreamSecurityValidator

The IFileStreamSecurityAnalyzer needs a single method to be implemented:

• IsConsideredSafe: This method should return false if the analyzer finds a reason not to trust the file

Example FileStreamSecurityAnalyzer

The following class shows how one could potentially guard against Cross-site scripting(XSS) vulnerabilities in an svg file.

public class SvgXssSecurityAnalyzer : IFileStreamSecurityAnalyzer
    {
        public bool ShouldHandle(Stream fileStream)
        {
            // reduce memory footprint by partially reading the file
            var startBuffer = new byte[256];
            var endBuffer = new byte[256];
            fileStream.Read(startBuffer);
            if (endBuffer.Length > fileStream.Length)
                fileStream.Seek(0, SeekOrigin.Begin);
            else
                fileStream.Seek(fileStream.Length - endBuffer.Length, SeekOrigin.Begin);
            fileStream.Read(endBuffer);
            var startString = System.Text.Encoding.UTF8.GetString(startBuffer);
            var endString = System.Text.Encoding.UTF8.GetString(endBuffer);
            return startString.Contains("<svg")
                   && startString.Contains("xmlns=\"http://www.w3.org/2000/svg\"")
                   && endString.Contains("/svg>");
        }

        public bool IsConsideredSafe(Stream fileStream)
        {
            var streamReader = new StreamReader(fileStream); // do not use a using as this will dispose of the underlying stream
            var fileContent = streamReader.ReadToEnd();
            return !(fileContent.Contains("<script") && fileContent.Contains("/script>"));
        }
    }

You can register it during startup or with a composer.

This is an example of registering the class with a composer:

public class ServerSideValidationComposer : IComposer
    {
        public void Compose(IUmbracoBuilder builder)
        {
            builder.Services.AddSingleton<IFileStreamSecurityAnalyzer, SvgXssSecurityAnalyzer>();
        }
    }

Then you can upload a file with the following content to the backoffice and see that it is not persisted.

<?xml version="1.0" standalone="no"?>
<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 1.1//EN" "http://www.w3.org/Graphics/SVG/1.1/DTD/svg11.dtd">

<svg version="1.1" baseProfile="full" xmlns="http://www.w3.org/2000/svg">
   <polygon id="triangle" points="0,0 0,50 50,0" fill="#009900" stroke="#004400"/>
   <script type="text/javascript">
      alert('xss');
   </script>
</svg>

The rich text editor is sanitized on the frontend by default, however, you may want to do this serverside as well. The libraries that are out there tend to have very strict, and therefore, problematic dependencies, so we'll leave it up to you how you want to sanitize the HTML.

Implementing your own IHtmlSanitizer

To make this task as easy as possible we've added an abstraction called IHtmlSanitizer, by default this doesn't do anything, but you can overwrite it with your own implementation to handle sanitization how you see fit. This interface only has a single method string Sanitize(string html), the output of this method is what will be stored in the database when you save a RichText editor.

To add your own sanitizer you must first create a class the implements the interface:

using Umbraco.Cms.Core.Security;

namespace MySite.HtmlSanitization
{
    public class MyHtmlSanitizer : IHtmlSanitizer
    {
        public string Sanitize(string html)
        {
            // Sanitize the html parameter here
            return "<h1>Sanitized HTML</h1>";
        }
    }
}

As you can see this specific implementation doesn't do a whole lot, but the Sanitize method is where you can use a library, or even your own sanitizer implementation, to sanitize the RichText editor input.

Now that you've added your own custom IHtmlSanitizer you must register it in the container to replace the existing NoOp sanitizer.

You can register it directly in the Startup.cs, for instance using an extension method on the IUmbracoBuilder:

Extension method:

using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Cms.Core.Security;
using Umbraco.Extensions;

namespace MySite.HtmlSanitization
{
    public static class BuilderExtensions
    {
        public static IUmbracoBuilder AddHtmlSanitizer(this IUmbracoBuilder builder)
        {
            builder.Services.AddUnique<IHtmlSanitizer, MyHtmlSanitizer>();
            return builder;
        }
    }
}

Calling the extension method:

        public void ConfigureServices(IServiceCollection services)
        {
#pragma warning disable IDE0022 // Use expression body for methods
            services.AddUmbraco(_env, _config)
                .AddBackOffice()
                .AddWebsite()
                .AddComposers()
                .AddHtmlSanitizer() // Call you extension method here.
                .Build();
#pragma warning restore IDE0022 // Use expression body for methods
        }

Or you can use a Composer:

using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Cms.Core.Security;
using Umbraco.Extensions;

namespace MySite.HtmlSanitization
{
    public class SanitizerComposer : IComposer
    {
        public void Compose(IUmbracoBuilder builder)
        {
            builder.Services.AddUnique<IHtmlSanitizer, MyHtmlSanitizer>();
        }
    }
}

If you've followed along you'll now see that no matter what you type in a Rich Text Editor, when you save it, it'll always only contain a heading that says "Sanitized HTML", this is of course isn't that helpful, but it shows that everything is working as expected, and that whatever your sanitizer returns is what will be saved.

Two-factor authentication (2FA) for Umbraco members is activated by implementing an ITwoFactorProvider interface and registering the implementation. The implementation can use third-party packages to archive for example support for authentication apps like Microsoft- or Google Authentication App.

Two-factor authentication for Members

Since Umbraco does not control how the UI is for member login and profile edit, the UI for 2FA is shipped as part of the snippets for macros. These can be used as a starting point, before styling the page as you would like.

Example implementation for Authenticator Apps for Members

In the following example, we will use the GoogleAuthenticator NuGet Package. Despite the name, this package works for both Google and Microsoft authenticator apps and can be used to generate the QR code needed to activate the app for the website.

using System;
using System.Threading.Tasks;
using Google.Authenticator;
using Umbraco.Cms.Core.Security;
using Umbraco.Cms.Core.Services;

namespace My.Website
{
    /// <summary>
    /// Model with the required data to setup the authentication app.
    /// </summary>
    public class QrCodeSetupData
    {
        /// <summary>
        /// The secret unique code for the user and this ITwoFactorProvider.
        /// </summary>
        public string Secret { get; init; }

        /// <summary>
        /// The SetupCode from the GoogleAuthenticator code.
        /// </summary>
        public SetupCode SetupCode { get; init; }
    }

    /// <summary>
    /// App Authenticator implementation of the ITwoFactorProvider
    /// </summary>
    public class UmbracoAppAuthenticator : ITwoFactorProvider
    {
        /// <summary>
        /// The unique name of the ITwoFactorProvider. This is saved in a constant for reusability.
        /// </summary>
        public const string Name = "UmbracoAppAuthenticator";

        private readonly IMemberService _memberService;

        /// <summary>
        /// Initializes a new instance of the <see cref="UmbracoAppAuthenticator"/> class.
        /// </summary>
        public UmbracoAppAuthenticator(IMemberService memberService)
        {
            _memberService = memberService;
        }

        /// <summary>
        /// The unique provider name of ITwoFactorProvider implementation.
        /// </summary>
        /// <remarks>
        /// This value will be saved in the database to connect the member with this  ITwoFactorProvider.
        /// </remarks>
        public string ProviderName => Name;

        /// <summary>
        /// Returns the required data to setup this specific ITwoFactorProvider implementation. In this case it will contain the url to the QR-Code and the secret.
        /// </summary>
        /// <param name="userOrMemberKey">The key of the user or member</param>
        /// <param name="secret">The secret that ensures only this user can connect to the authenticator app</param>
        /// <returns>The required data to setup the authenticator app</returns>
        public Task<object> GetSetupDataAsync(Guid userOrMemberKey, string secret)
        {
            var member = _memberService.GetByKey(userOrMemberKey);

            var twoFactorAuthenticator = new TwoFactorAuthenticator();
            SetupCode setupInfo = twoFactorAuthenticator.GenerateSetupCode("My application name", member.Username, secret, false);
            return Task.FromResult<object>(new QrCodeSetupData()
            {
                SetupCode = setupInfo,
                Secret = secret
            });
        }

        /// <summary>
        /// Validated the code and the secret of the user.
        /// </summary>
        public bool ValidateTwoFactorPIN(string secret, string code)
        {
            var twoFactorAuthenticator = new TwoFactorAuthenticator();
            return twoFactorAuthenticator.ValidateTwoFactorPIN(secret, code);
        }

        /// <summary>
        /// Validated the two factor setup
        /// </summary>
        /// <remarks>Called to confirm the setup of two factor on the user. In this case we confirm in the same way as we login by validating the PIN.</remarks>
        public bool ValidateTwoFactorSetup(string secret, string token) => ValidateTwoFactorPIN(secret, token);
    }
}

First, we create a model with the information required to set up the 2FA provider and then we implement the ITwoFactorProvider with the use of the TwoFactorAuthenticator from the GoogleAuthenticator NuGet package.

Now we need to register the UmbracoAppAuthenticator implementation. This can be done on the IUmbracoBuilder in your startup or a composer.

using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Cms.Core.Security;
using Umbraco.Extensions;

namespace My.Website
{
    public class UmbracoAppAuthenticatorComposer : IComposer
    {
        public void Compose(IUmbracoBuilder builder)
        {
            var identityBuilder = new MemberIdentityBuilder(builder.Services);
            identityBuilder.AddTwoFactorProvider<UmbracoAppAuthenticator>(UmbracoAppAuthenticator.Name);
        }
    }
}

At this point, the 2FA is active, but no members have set up 2FA yet. The setup of 2FA depends on the type. In the case of App Authenticator, we will add the following to our view showing the edit profile of the member.

@using Umbraco.Cms.Core.Services
@using Umbraco.Cms.Web.Website.Controllers
@using Umbraco.Cms.Web.Website.Models
@using My.Website  @* Or whatever your namespace with the QrCodeSetupData model is *@
@inject MemberModelBuilderFactory memberModelBuilderFactory
@inject ITwoFactorLoginService twoFactorLoginService
@{
    // Build a profile model to edit
    var profileModel = await memberModelBuilderFactory
        .CreateProfileModel()
        .BuildForCurrentMemberAsync();

    // Show all two factor providers
    var providerNames = twoFactorLoginService.GetAllProviderNames();
    if (providerNames.Any())
    {
        <div asp-validation-summary="All" class="text-danger"></div>
        foreach (var providerName in providerNames)
        {
            var setupData = await twoFactorLoginService.GetSetupInfoAsync(profileModel.Key, providerName);
            if (setupData is null)
            {
                @using (Html.BeginUmbracoForm<UmbTwoFactorLoginController>(nameof(UmbTwoFactorLoginController.Disable)))
                {
                    <input type="hidden" name="providerName" value="@providerName"/>
                    <button type="submit">Disable @providerName</button>
                }
            }
            else if(setupData is QrCodeSetupData qrCodeSetupData)
            {
                @using (Html.BeginUmbracoForm<UmbTwoFactorLoginController>(nameof(UmbTwoFactorLoginController.ValidateAndSaveSetup)))
                {
                    <h3>Setup @providerName</h3>
                    <img src="@qrCodeSetupData.SetupCode.QrCodeSetupImageUrl"/>
                    <p>Scan the code above with your authenticator app <br /> and enter the resulting code here to validate:</p>
                    <input type="hidden" name="providerName" value="@providerName"  />
                    <input type="hidden" name="secret" value="@qrCodeSetupData.Secret"  />
                    <input type="text" name="code"  />
                    <button type="submit">Validate & save</button>
                }
            }
        }
    }
}

In this razor-code sample, we get the current member's unique key and list all registered ITwoFactorProvider implementations.

If the setupData is null for the specified providerName it means the provider is already set up. In this case, we show a disable button. Otherwise, we check the type and show the UI for how to set up the App Authenticator, by showing the QR Code and an input field to validate the code from the App Authenticator.

The last part required is to use the Login Partial Macro snippet.

Notification when 2FA is requested for a member

When a 2FA login is requested for a member, the MemberTwoFactorRequestedNotification is published. This notification can also be used to send the member a one-time password via e-mail or phone. Even though these 2FA types are not considered secure as App Authentication, it is still a massive improvement compared to no 2FA.

Two-factor authentication for Users

Umbraco controls how the UI is for user login and user edits, but will still need a view for configuring each 2FA provider.

Example implementation for Authenticator Apps for Users

In the following example, we will use the GoogleAuthenticator NuGet Package. Despite the name, this package works for both Google and Microsoft authenticator apps and can be used to generate the QR code needed to activate the app for the website.

using System.Runtime.Serialization;
using Google.Authenticator;
using Umbraco.Cms.Core.Security;
using Umbraco.Cms.Core.Services;
using Umbraco.Extensions;

namespace My.Website
{
    [DataContract]
    public class TwoFactorAuthInfo
    {
        [DataMember(Name = "qrCodeSetupImageUrl")]
        public string? QrCodeSetupImageUrl { get; set; }

        [DataMember(Name = "secret")]
        public string? Secret { get; set; }
    }

    /// <summary>
    /// App Authenticator implementation of the ITwoFactorProvider
    /// </summary>
    public class UmbracoUserAppAuthenticator : ITwoFactorProvider
    {
        private readonly IUserService _userService;

        /// <summary>
        /// The unique name of the ITwoFactorProvider. This is saved in a constant for reusability.
        /// </summary>
        public const string Name = "UmbracoUserAppAuthenticator";

        /// <summary>
        /// Initializes a new instance of the <see cref="UmbracoAppAuthenticator"/> class.
        /// </summary>
        public UmbracoUserAppAuthenticator(IUserService userService)
        {
            _userService = userService;

        }

        /// <summary>
        /// The unique provider name of ITwoFactorProvider implementation.
        /// </summary>
        /// <remarks>
        /// This value will be saved in the database to connect the member with this  ITwoFactorProvider.
        /// </remarks>
        public string ProviderName => Name;

        /// <summary>
        /// Returns the required data to setup this specific ITwoFactorProvider implementation. In this case it will contain the url to the QR-Code and the secret.
        /// </summary>
        /// <param name="userOrMemberKey">The key of the user or member</param>
        /// <param name="secret">The secret that ensures only this user can connect to the authenticator app</param>
        /// <returns>The required data to setup the authenticator app</returns>
        public Task<object> GetSetupDataAsync(Guid userOrMemberKey, string secret)
        {
            var user = _userService.GetByKey(userOrMemberKey);

            var twoFactorAuthenticator = new TwoFactorAuthenticator();
            SetupCode setupInfo = twoFactorAuthenticator.GenerateSetupCode("My application name", user.Username, secret, false);
            return Task.FromResult<object>(new TwoFactorAuthInfo()
            {
                QrCodeSetupImageUrl = setupInfo.QrCodeSetupImageUrl,
                Secret = secret
            });
        }

        /// <summary>
        /// Validated the code and the secret of the user.
        /// </summary>
        public bool ValidateTwoFactorPIN(string secret, string code)
        {
            var twoFactorAuthenticator = new TwoFactorAuthenticator();
            return twoFactorAuthenticator.ValidateTwoFactorPIN(secret, code);
        }

        /// <summary>
        /// Validated the two factor setup
        /// </summary>
        /// <remarks>Called to confirm the setup of two factor on the user. In this case we confirm in the same way as we login by validating the PIN.</remarks>
        public bool ValidateTwoFactorSetup(string secret, string token) => ValidateTwoFactorPIN(secret, token);
    }
}

using System;
using System.Runtime.Serialization;
using System.Threading.Tasks;
using Google.Authenticator;
using Umbraco.Cms.Core.Security;
using Umbraco.Cms.Core.Services;
using Umbraco.Extensions;

namespace My.Website
{
    [DataContract]
    public class TwoFactorAuthInfo
    {
        [DataMember(Name = "qrCodeSetupImageUrl")]
        public string QrCodeSetupImageUrl { get; set; }

        [DataMember(Name = "secret")]
        public string Secret { get; set; }
    }

    /// <summary>
    /// App Authenticator implementation of the ITwoFactorProvider
    /// </summary>
    public class UmbracoUserAppAuthenticator : ITwoFactorProvider
    {
        private readonly IUserService _userService;

        /// <summary>
        /// The unique name of the ITwoFactorProvider. This is saved in a constant for reusability.
        /// </summary>
        public const string Name = "UmbracoUserAppAuthenticator";

        /// <summary>
        /// Initializes a new instance of the <see cref="UmbracoAppAuthenticator"/> class.
        /// </summary>
        public UmbracoUserAppAuthenticator(IUserService userService)
        {
            _userService = userService;

        }

        /// <summary>
        /// The unique provider name of ITwoFactorProvider implementation.
        /// </summary>
        /// <remarks>
        /// This value will be saved in the database to connect the member with this  ITwoFactorProvider.
        /// </remarks>
        public string ProviderName => Name;

        /// <summary>
        /// Returns the required data to setup this specific ITwoFactorProvider implementation. In this case it will contain the url to the QR-Code and the secret.
        /// </summary>
        /// <param name="userOrMemberKey">The key of the user or member</param>
        /// <param name="secret">The secret that ensures only this user can connect to the authenticator app</param>
        /// <returns>The required data to setup the authenticator app</returns>
        public Task<object> GetSetupDataAsync(Guid userOrMemberKey, string secret)
        {
            var user = _userService.GetByKey(userOrMemberKey);

            var twoFactorAuthenticator = new TwoFactorAuthenticator();
            SetupCode setupInfo = twoFactorAuthenticator.GenerateSetupCode("My application name", user.Username, secret, false);
            return Task.FromResult<object>(new TwoFactorAuthInfo()
            {
                QrCodeSetupImageUrl = setupInfo.QrCodeSetupImageUrl,
                Secret = secret
            });
        }

        /// <summary>
        /// Validated the code and the secret of the user.
        /// </summary>
        public bool ValidateTwoFactorPIN(string secret, string code)
        {
            var twoFactorAuthenticator = new TwoFactorAuthenticator();
            return twoFactorAuthenticator.ValidateTwoFactorPIN(secret, code);
        }

        /// <summary>
        /// Validated the two factor setup
        /// </summary>
        /// <remarks>Called to confirm the setup of two factor on the user. In this case we confirm in the same way as we login by validating the PIN.</remarks>
        public bool ValidateTwoFactorSetup(string secret, string token) => ValidateTwoFactorPIN(secret, token);
    }
}

First, we create a model with the information required to set up the 2FA provider and then we implement the ITwoFactorProvider with the use of the TwoFactorAuthenticator from the GoogleAuthenticator NuGet package.

Now we need to register the UmbracoUserAppAuthenticator implementation and the view to show to set up this provider. This can be done on the IUmbracoBuilder in your startup or a composer.

using Microsoft.Extensions.DependencyInjection;
using Umbraco.Cms.Core.Composing;
using Umbraco.Cms.Core.DependencyInjection;
using Umbraco.Cms.Core.Security;
using Umbraco.Cms.Web.BackOffice.Security;
using Umbraco.Extensions;

namespace My.Website
{
    public class UmbracoAppAuthenticatorComposer : IComposer
    {
        public void Compose(IUmbracoBuilder builder)
        {
            var identityBuilder = new BackOfficeIdentityBuilder(builder.Services);

            identityBuilder.AddTwoFactorProvider<UmbracoUserAppAuthenticator>(UmbracoUserAppAuthenticator.Name);

            builder.Services.Configure<TwoFactorLoginViewOptions>(UmbracoUserAppAuthenticator.Name, options =>
            {
                options.SetupViewPath = "..\\App_Plugins\\TwoFactorProviders\\twoFactorProviderGoogleAuthenticator.html";
            });
        }
    }
}

Now we need to create the view we just configured, in the path we choose.

<div ng-controller="CustomCode.TwoFactorProviderGoogleAuthenticator as vm">

  <umb-editor-view ng-cloak>

    <form name="vm.authForm" method="POST" ng-submit="vm.validateAndSave()">

      <umb-editor-header name="vm.title" name-locked="true" hide-alias="true" hide-icon="true" hide-description="true">
      </umb-editor-header>

      <umb-editor-container>

        <umb-box>

          <umb-box-header title="Setup information"></umb-box-header>

          <umb-box-content>

            <div class="control-group text-center">
              <img alt="QR code for Google Authenticator" ng-src="{{vm.qrCodeImageUrl}}" ng-if="vm.qrCodeImageUrl" />
            </div>

            <umb-control-group label-for="token" alias="2facode"
              label="Scan with your authenticator app and enter the code:" required="true">

              <input umb-auto-focus id="2facode" class="-full-width-input input-xlarge" type="text" name="token"
                inputmode="numeric" autocomplete="one-time-code" ng-model="vm.code" localize="placeholder"
                placeholder="@login_2faCodeInputHelp" aria-required="true" required />

              <div ng-messages="vm.authForm.token.$error" role="alert">
                <span class="umb-validation-label" ng-message="token">
                  <localize key="login_2faInvalidCode">Invalid code entered</localize>
                </span>
              </div>

            </umb-control-group>

          </umb-box-content>

        </umb-box>

      </umb-editor-container>

      <umb-editor-footer>

        <umb-editor-footer-content-right>

          <umb-button type="button" button-style="link" label-key="general_close" shortcut="esc" action="vm.close()">
          </umb-button>

          <umb-button state="vm.buttonState" button-style="success" label-key="buttons_save" type="submit"
            disabled="vm.code.length === 0">
          </umb-button>

        </umb-editor-footer-content-right>

      </umb-editor-footer>

    </form>

  </umb-editor-view>

</div>

As this view uses an angular controller, we need to create that class and configure it in the package.manifest.

In package.manifest, we point to the path of the angular controller that we are creating in the next step.

{
  "javascript": [
    "~/App_Plugins/TwoFactorProviders/twoFactorProviderGoogleAuthenticator.controller.js"
  ]
}

And we create the controller in that location:

!(function () {
  "use strict";

  const googleTwoFactorProviderCtrl = [
    '$scope', 'twoFactorLoginResource', 'notificationsService',
    function ($scope, twoFactorLoginResource, notificationsService) {
      const vm = this;

      vm.title = "Setup Google Authenticator on " + $scope.model?.user?.name;
      vm.providerName = $scope.model?.providerName;
      vm.qrCodeImageUrl = "";
      vm.secret = "";
      vm.code = "";
      vm.authForm = {};
      vm.buttonState = "init";

      vm.close = close;
      vm.validateAndSave = validateAndSave;

      function init() {
        vm.buttonState = "init";
        twoFactorLoginResource.setupInfo(vm.providerName)
          .then(function (response) {
            // This response is the model I defined to be returned from ITwoFactorProvider.GetSetupDataAsync
            vm.qrCodeImageUrl = response.qrCodeSetupImageUrl;
            vm.secret = response.secret;
          })
          .catch(function () {
            notificationsService.error("Could not fetch login info");
          });
      }

      function validateAndSave() {
        vm.authForm.token.$setValidity("token", true);
        vm.buttonState = "busy";

        twoFactorLoginResource.validateAndSave(vm.providerName, vm.secret, vm.code)
          .then(function (successful) {

            if (successful) {
              notificationsService.success("Two-factor authentication has successfully been enabled");
              vm.buttonState = "success";
              close();
            } else {
              vm.authForm.token.$setValidity("token", false);
              vm.buttonState = "error";
            }

          })
          .catch(function (error) {
            notificationsService.error(error);
            vm.buttonState = "error";
          });
      }

      function close() {
        if ($scope.model.close) {
          $scope.model.close();
        }
      }

      init();
    }
  ];

  angular.module("umbraco").controller("CustomCode.TwoFactorProviderGoogleAuthenticator", googleTwoFactorProviderCtrl);
})();

At this point, the 2FA is active, but no users have set up 2FA yet.

Each user can now enable the configured 2fa providers on their user. This can be done from the user panel by clicking the user avatar.

When clicking the Configure Two-Factor button, a new panel is shown, listing all enabled two-factor providers.

When clicking Enable on one of these, the configured view for the specific provider will be shown

When the authenticator is enabled correctly, a disable button is shown instead.

To disable the two-factor authentication on your user, it is required to enter the verification code, otherwise, admins are allowed to disable providers on other users.

Notification when 2FA is requested for a user

When a 2FA login is requested for a user, the UserTwoFactorRequestedNotification is published. This notification can also be used to send the user a one-time password via e-mail or phone, even though these 2FA types are not considered secure as App Authentication, it is still a massive improvement compared to no 2FA.