Why App-Based MFA Is Better Than SMS: A 2025 Guide for Secure Authentication

Multi-factor authentication (MFA) is a must-have for protecting business and personal accounts. But not all MFA methods are created equal. As cyber threats grow more sophisticated, security experts and federal agencies increasingly recommend app-based MFA (using authenticator apps like Microsoft Authenticator or Google Authenticator) over SMS-based MFA. Here’s why. 

SMS-Based MFA: Convenient but Vulnerable

SMS-based MFA sends a one-time code to your phone via text message. While better than no MFA, this method has several well-documented weaknesses: 

• SIM Swapping Attacks: Criminals can trick or bribe mobile carriers into transferring your phone number to a new SIM card they control, intercepting your SMS codes and locking you out of your accounts. 

• Phishing and Social Engineering: Attackers can lure users to fake login pages or pose as support staff to trick them into sharing SMS codes. 

• Man-in-the-Middle Attacks & SS7 Vulnerabilities: SMS messages are not encrypted and can be intercepted as they travel over mobile networks, especially through flaws in the SS7 protocol. 

• Malware Risks: Malware on your phone can access SMS messages and steal authentication codes. 

• Network Dependence: SMS relies on cellular networks, which can be disrupted by outages or poor coverage, leaving you unable to receive codes when you need them most. 

These vulnerabilities have led the FBI, CISA, and NIST to issue warnings and guidance against relying on SMS-based MFA, especially for sensitive or high-value accounts. 

App-Based MFA: Stronger by Design 

Authenticator apps generate time-based one-time passwords (TOTPs) directly on your device, independent of your phone number or carrier. This approach offers several key advantages: 

• Immune to SIM Swapping: Codes are generated on your device and are not tied to your phone number, so SIM swap attacks are ineffective. 

• No Interception in Transit: Codes never travel over the cellular network or the internet, making them immune to interception via SS7 or man-in-the-middle attacks. 

• Resistant to Phishing: Since codes are generated within the app and not sent externally, attackers can’t simply intercept them. Many authenticator apps now support number-matching or biometric authentication for added protection. 

• Offline Access: Authenticator apps work even without internet or cellular service, ensuring you can always access your codes. 

• Short Lifespan: Codes typically expire every 30–60 seconds, reducing the window for misuse. 

• Centralized Management: You can manage multiple accounts from a single app, often with options for secure backup and recovery. 

Real-World Impact 

The difference in security isn’t just theoretical. Data from major platforms like Coinbase show that while SMS-based 2FA is widely used, the vast majority of successful account takeovers exploit SMS-protected accounts. In contrast, app-based MFA dramatically reduces the risk of unauthorized access. 

Security Community and Agency Recommendations 

 

FBI & CISA: Both agencies now explicitly warn against SMS-based MFA and urge the use of app-based or hardware-based authentication methods for sensitive accounts. 

NIST: The National Institute of Standards and Technology restricts the use of SMS for MFA in its guidelines, citing interception and SIM swap risks. 

Microsoft & Security Experts: Leading security professionals recommend moving away from SMS and voice call authentication in favor of app-based or hardware keys. 

What About Downsides? 

The main risk with authenticator apps is losing access if your device is lost or the app is deleted. However, most services now provide recovery codes or allow you to register multiple devices. Always set up backup options and store recovery codes in a safe place.

In addition, setting up MFA with an authenticator app requires action by the user and requires some technical capability. For some user populations — for example who have limited technical acumen or consistent access to a smartphone — this may not be practical or sustainable. 

Summing It Up 

App-based MFA offers a much higher level of security than SMS-based MFA, shielding your accounts from SIM swapping, interception, and phishing attacks. This method is strongly endorsed by cybersecurity experts and leading agencies around the globe.  

If you haven’t made the switch yet, now is the time to upgrade your protection by using an authenticator app — and encourage your colleagues or team to follow suit. While any form of multi-factor authentication is better than relying on passwords alone, app-based MFA stands out as the most secure and reliable choice for safeguarding your digital life in 2025.