The SMS OTP (One-Time Password) method is more vulnerable to interception compared to TOTP (Time- based One-Time Password) because SMS messages can be intercepted through various attack vectors like SIM swapping or SMS phishing. TOTP, on the other hand, generates codes directly on the device and does not rely on a communication channel like SMS, making it less susceptible to interception.
References = CompTIA Security+ SY0-701 study materials, particularly in the domain of identity and access management.