Two-factor authentication (2FA) adds an essential layer of security to your online accounts, but not all methods are equally secure. Many rely on SMS-based 2FA, assuming it’s a safe option. Unfortunately, SMS is far from reliable. Here’s why I stopped using SMS for 2FA and what I use instead.
SIM Swapping: A Major Risk
One of the biggest dangers of SMS-based 2FA is SIM swapping, where attackers trick your mobile carrier into transferring your phone number to a new SIM card. With control of your number, they can intercept any SMS, including 2FA codes intended to secure your accounts.
Here’s how it works: attackers impersonate you, using stolen personal details like your address or the last four digits of your social security number. Once they convince the carrier to transfer your number, they can intercept your text messages and gain access to your accounts linked to your phone number.
SMS Messages Are Vulnerable to Interception
Even if you avoid SIM swapping, SMS itself isn’t secure. Texts are transmitted over networks that can be exploited. For example, attackers can leverage vulnerabilities in the Signaling System No. 7 (SS7) protocol, used globally by telecoms, to intercept messages without needing access to your device.
Additionally, malware or spyware on your device can monitor incoming SMS messages and forward 2FA codes to attackers. Since SMS lacks encryption, these codes are vulnerable at every transmission step.
Dependence on Your Phone Number
Another issue with SMS-based 2FA is its reliance on your mobile number. If you’re in an area with poor cellular coverage, you won’t receive codes even if you have Wi-Fi. This makes SMS less reliable than alternatives that work through an internet connection.
What Do We Recommend: Authentication Apps
We recommend using authentication apps like Google Authenticator, Microsoft Authenticator, and Authy for 2FA. These apps generate time-based one-time passwords (TOTP) directly on your device, providing a safer and more reliable alternative to SMS.
Why authentication apps are better:
- Security: Codes are generated locally on your device and don’t pass through potentially compromised mobile networks.
- Offline Functionality:Â These apps work without an internet or cellular connection, so you can access your codes anywhere.
- Additional Protection:Â Many apps offer features like password or biometric authentication to secure access to the codes.
Authy offers encrypted cloud backups, making it easier to recover accounts if you lose your phone. Google Authenticator is another popular, free option that’s easy to set up.
Using an authentication app is simple. Once configured, usually by scanning a QR code during account setup, you open the app to retrieve a code, which refreshes every 30 seconds. This ensures that even if a code is stolen, it becomes useless almost immediately.
Conclusion
While 2FA protects your accounts, the method you choose matters significantly. SMS-based 2FA is riddled with vulnerabilities—from SIM swapping to message interception and practical issues like poor cellular coverage. Authentication apps offer a far more secure and user-friendly alternative, ensuring that your accounts remain protected without exposing you to these risks.
