Multi-factor authentication for Mendix

What is Multi-factor Authentication?

Multi-factor authentication (MFA; also known as Two-factor authentication or 2FA, along with similar terms) is an electronic authentication method in which a user is granted access to a website or application only after successfully presenting two or more pieces of evidence (or factors) to an authentication mechanism: knowledge (something only the user knows), possession (something only the user has), and inherence (something only the user is). MFA protects the user from an unknown person trying to access their data such as personal ID details or financial assets.

A third-party authenticator (TPA) app enables two-factor authentication, usually by showing a randomly generated and constantly refreshing code to use for authentication. (source:Wikipedia)

What is the problem we solve?

The available multi-factor implementations in the Marketplace offer the end-user of an Mendix application during the login procedure to enter the code from a SMS, E-mail or generated by an authenticator (Google) after the actual login (and creation of the user session). See the diagram below:

https://swimlanes.io/d/zEPQlLV3T

At a successful login and prior to entering an MFA code, the user already has a valid user session and access to the user's authorized pages, microflows etc. (but you cannot see them nor easy access them). This approach only works when dynamic role assignment is done after a valid MFA code (which is not default Mendix functionality).

What is the solution?

We have built a MFA module that extends the Mendix LoginAction, documented at https://apidocs.rnd.mendix.com/7/runtime/com/mendix/core/action/user/LoginAction.html The MFA code is validated first and only then the module creates a user session which grants the user access to their pages, microflows etc.

https://swimlanes.io/u/4o7jaAOjY

How did we prove that this module is secure?

At the point in time after login in the first step:

mx.data.get({ xpath:"//System.User", callback:function(data){console.log(data);} })

still returns the anonymous User object:

Scenarios to cover:

• Default login via login.html for accounts with MFA disabled.
• Default login via widgets for accounts with MFA disabled.
• Default login for webservice and REST accounts.
• Login by a customized login.html with MFA enabled (login-with-mfa.html + login-mfa.js + Authenticator app code only. Not compatible code sent by SMS or E-mail).
• Login by default widgets but extended with ability to enter MFA code with MFA enabled.

Configuration

Download the module from the Mendix Marketplace here:

Or from Github: https://github.com/appronto/multifactor-authentication

There are a few things to configure:

After startup configuration:

1. Add ASU_MFA Microflow in your After Startup.

2. Change SUB_MFA_UserDisabledCheck to call your logic to determine if the logged in user needs to be multi-factor authenticated. Add the new attributes HasMFAenabled(Boolean) and LastLogin2FA (datetime) to the Account entity.

3. Add your method(s) of multifactor authentication in SUB_ValidateMFAforUser:

3 samples available:

• Google authenticator connector
  • Module download: https://marketplace.mendix.com/link/component/2948
  • Google Play Store: https://play.google.com/store/apps/details?id=com.google.android.apps.authenticator2&hl=en
  • Apple App store: https://apps.apple.com/us/app/google-authenticator/id388497605
• SMS
  • Change SUB_InformMFACodeForUser to send the SMS
  • Send a SMS with for example Twilio:
  • Try Twilio here: http://appron.to/try-twilio and create an API key on https://www.twilio.com/console/project/settings
• Email verification with code to verify
  • Change SUB_InformMFACodeForUser to send the e-mail
  • Use default Emailtemplate module or Sendgrid API for example to compose this e-mail to your user.

4. Add snippet SN_MFA_LoginPage to your login page

5. If applicable move thelogin-with-mfa.html and js/login-mfa.js from the resources directory to your theme directory to support login actions with MFA from these pages.

6. Set the constant EnabledMFA to true to get started!

Keep in mind when upgrading the module from the Appstore in the future:

It will break the login mechanism, but you will be notified because by default an exception will be raised when the module with your MFA logic hasn't been configured correcty. Like this "An error has occurred while handling the request: java.lang.Exception: Create code not yet implemented".

What we learned

We preferred a non-persistent approach to keep track of the anonymous user login steps (first with login, second with MFA code). We found out when the first attempt was successfully validated, in the second step when passing the MFA code, the context/relation to the previous anonymous session was deleted. Therefore we could not correlate this to the first step. When we use a persistent MFA entity (and commit the MFA object after the first login step) it works.

Advanced java challenges:

When extending the LoginAction class and trying to set parameters from this class in our extended class, we found out this was not possible in combination with the super.execute() method. We decided to use createSession. We have already validated the username and password in the first step and the MFA object can't be modified/created by the anonymous user (and is also checked twice).

We also wanted the module to be compatible via a login.html variant and the custom login-with-mfa.html. Therefore, it is necessary to send the MFA code together with your username and password. We need to pass this MFA code through the header because the payload is stripped by the Core LoginAction functionality.

Login-with-mfa.html:

Login-mfa.js:

MultiFactorAuthLoginAction.java:

Please report issues

Have you found an issue or a vulnerability in this module, please reach out to pim@appronto.nl. I will reward you with a nice goodie bag and will publish the new version to the Marketplace.