Multi-Factor Authentication (MFA) - Why It Matters

About 2 min read

Multi-factor authentication (MFA) is a method of verifying identity by combining two or more different factors during authentication. By combining several categories among knowledge factors (passwords), possession factors (smartphones, security keys), and inherence factors (fingerprints, faces), it significantly strengthens security. According to a 2024 Microsoft study, accounts with MFA enabled can prevent more than 99.9% of unauthorized access, and this trend remains unchanged as of 2025. Google and Apple are also working to enable MFA by default in their own services.

Real-World Use Cases

"After making MFA mandatory across the entire company, unauthorized logins via phishing emails dropped by 98% year over year. In particular, administrator accounts that adopted FIDO2 security keys had zero cases of unauthorized access in the year following the rollout."

Comparison of Authentication Factors

The Three Authentication Factors and Practical Choices

Knowledge factors prove "something you know," such as passwords or PINs; possession factors prove "something you have," such as smartphones or hardware tokens; and inherence factors prove "something you are," such as fingerprints or faces. In practice, SMS authentication is vulnerable to SIM swapping attacks, so TOTP apps (Google Authenticator, Authy) and FIDO2 security keys (YubiKey) are recommended instead. In particular, for financial institutions and administrator accounts, you should choose TOTP or hardware keys.multi-factor authentication books on Amazon let you learn about it systematically.

The Difference from Two-Step Verification (2FA)

Two-step verification (2FA) refers to "authenticating in two steps," while MFA refers to "authenticating with two or more different factors." For example, a method that asks a security question after entering a password is two steps, but since both are knowledge factors, it cannot be called MFA. A combination of a password and a TOTP code is a knowledge factor plus a possession factor, so it is two-step verification and at the same time MFA. From a security standpoint, combining factors from different categories is more important than the number of steps.

Key Points for Deploying and Operating MFA

Combining a sufficiently long, random password (a knowledge factor) with a TOTP app or security key (a possession factor) achieves robust multi-factor authentication. A key consideration during deployment is the secure storage of recovery codes. To prepare for the loss or failure of a device, always set up a backup authentication method. In corporate environments, it is effective to make MFA mandatory across the entire company together with a password policy, and to inform employees about the two-step verification setup guide.account security books (Amazon) are also helpful references.