Multi-Factor Authentication (MFA)
Multi-factor authentication (MFA) is a security mechanism that requires users to provide two or more independent verification factors to prove their identity before granting access to a system or resource.
Multi-factor authentication (MFA) strengthens the authentication process by requiring users to present multiple forms of evidence to verify their identity. Authentication factors fall into three categories: something you know (passwords, PINs), something you have (security tokens, smartphones, smart cards), and something you are (biometrics like fingerprints, facial recognition, or iris scans). By combining factors from different categories, MFA ensures that the compromise of one factor alone is insufficient for an attacker to gain access.
Common MFA implementations include SMS-based one-time passwords (OTP), authenticator app-generated time-based OTPs (TOTP), push notifications sent to registered devices, hardware security keys (FIDO2/WebAuthn), biometric verification, and email-based verification codes. The security strength varies significantly across these methods. SMS-based MFA is considered the weakest due to SIM swapping and interception risks, while hardware security keys provide the strongest protection against phishing and account takeover.
MFA has become a critical security control as password-based authentication alone has proven insufficient against modern threats. Credential stuffing attacks exploit reused passwords. Phishing attacks capture passwords in real time. Password spraying attacks test common passwords across many accounts. MFA mitigates these threats by adding a layer that cannot be easily stolen or guessed remotely. Studies consistently show that enabling MFA blocks over 99% of automated account compromise attempts.
Despite its effectiveness, MFA is not infallible. Sophisticated attackers use techniques like MFA fatigue (bombarding users with push notifications), adversary-in-the-middle proxies that intercept MFA tokens in real time, and social engineering to bypass MFA protections. Organizations should adopt phishing-resistant MFA methods such as FIDO2 security keys, implement conditional access policies, monitor for MFA bypass attempts, and educate users about emerging threats to MFA.