Which method uses SMS codes for two-factor authentication but is vulnerable to interception?

Which method uses SMS codes for two-factor authentication but is vulnerable to interception?

• A. Personal USB Key
• B. Fingerprint Authentication
• C. Hand Geometry
• D. Text Message Authentication

Answer: (D)

Text Message Authentication uses one-time codes sent to a user’s phone over the SMS network as the second factor. This approach adds a layer of security, but the channel it relies on is inherently vulnerable because messages travel through telecom networks that can be intercepted or redirected. Attackers can exploit SIM swap to take over a phone number, abuse SS7 weaknesses to divert or intercept messages, or compromise a device to read incoming texts. Because the code travels outside the user’s direct control, it can be captured and used by an attacker to gain access if the password is known. By contrast, a hardware USB key provides a physical token that isn’t sent over the phone network, and biometrics verify identity locally on the device, without exposing codes over a network. This makes text-based codes one of the more vulnerable 2FA options among the given choices.

Text Message Authentication uses one-time codes sent to a user’s phone over the SMS network as the second factor. This approach adds a layer of security, but the channel it relies on is inherently vulnerable because messages travel through telecom networks that can be intercepted or redirected. Attackers can exploit SIM swap to take over a phone number, abuse SS7 weaknesses to divert or intercept messages, or compromise a device to read incoming texts. Because the code travels outside the user’s direct control, it can be captured and used by an attacker to gain access if the password is known. By contrast, a hardware USB key provides a physical token that isn’t sent over the phone network, and biometrics verify identity locally on the device, without exposing codes over a network. This makes text-based codes one of the more vulnerable 2FA options among the given choices.