Which level of authentication?

 Did you ever ask yourself which level of authentication is required to secure the infrastructure access? Recently the Multi-Factor Authentication (MFA) solutions are one of the greatest ways of securing every IT infrastructure and also improving the identity management platforms. Regardless of each action for IT security hardening, MFAs are the most powerful way to increase the organizational user's authentication procedure, especially whenever you mix it with PAM/IAM solutions. But what information is required to understand and select a suitable solution? First of all, we need to decide exactly which level of authentication is based on our network architecture, types of internal or external incoming authentication requests, and risk level of corresponding data/service through this method of access. Truly based on each authentication level consideration, you can decide how many AUTH factors and finally which solution is the best for you:

1. SFA: Although the single-factor is the easiest way, it's ideal for situations the user has no options to input his/her credentials into the system. For example, inside an industrial environment where may no keyboard exists for authentication, SFA is the best solution. Most of the SFAs are included with biometric factors like face detection, fingerprinting, or eye scanners. So regardless of SFA nature, it's a secure way, especially for OT networks.
2. 2FA: Two-factor authentication is the most popular method because it can easily block more than 90% of threats like Brute-Forcing, Password Guessing, and Library Attacks. Regardless of the possible limitations of any selected solution, I strongly suggest considering the SSO (Single Sign-On) attributes of your 2FA system. I mean 2FA should be compatible with regular authentication services like Microsoft Active Directory, or any common LDAP services. Because it can reduce the rate of general complexity of 2FA/MFA systems. Corresponding to the traditional first level of authentication and also SSO/SAML integration, you can select the suitable option for your infra.
3. MFA: Increasing the level of AUTH, will totally increase the security measures. But you shouldn't avoid inhabiting factors like the knowledge of users about how to efficiently use each authentication level of configured MFA system. Next, we should obtain a failover option at each authentication level. For example, a Help Desk team quickly reset TOTP paired tokens for problematic users. Or select a backup solution if a user loses their hardware token or lost his/her smartphone with the software(App) token. Mixing the hardware/software solutions and using an easy-to-use biometric method like an eye-scanner inside the hard-working areas of your organization, as the replacement of regular TOTP-based Tokens.

 Employment of all AUTH levels from the same provider can increase integration and compatibility rate, but make the system vulnerable to unknown architectural bugs like the Zero-Days of company products. Combining with a 3rd-party solution increases both the security and complexity properties of the design, so you should consider all aspects of MFA system maintenance.

 In the conclusion, I think before constructing the final authentication system, check the integration rate of each selected AUTH level with their similar solutions, and then consider a backup way if you lose physical/logical access to the provided tokens. 

 Congrats, and enjoy your MFA solution.