SMS-based two-factor authentication is no longer considered one of the most secure authentication methods. While it offers better protection than passwords alone, SMS 2FA remains vulnerable to SIM swapping, message interception and social engineering attacks. Many organizations now recommend authenticator apps, passkeys or hardware security keys instead.
In this article, we’ll explain:
- the key security risks of SMS 2FA
- why it’s no longer considered best practice
- and the safer authentication methods businesses should use instead
If you’re currently using SMS verification codes, the better question is not whether SMS 2FA works, but whether it remains the strongest option available.
Why Is SMS 2FA No Longer Considered a Secure Authentication Method?
While it adds a layer of protection beyond passwords, it is vulnerable to:
- SIM swapping attacks
- SMS interception
- Social engineering
- Device and carrier-level exploits
Because of these risks, many organizations now recommend using app-based authentication or hardware tokens instead of SMS 2FA.
Choosing a stronger authentication method is an important step—but it’s only one part of a broader security strategy. In many environments, attackers aren’t trying to break MFA anymore. They’re finding ways around it. Techniques like token theft allow someone to access an account after login without triggering another authentication challenge. We break down how that works and why it’s becoming more common in this post on how attackers bypass MFA using token theft.
If you’re evaluating how to strengthen your organization’s security posture, the next step is understanding where those gaps exist and how they connect through a more strategic IT approach, such as Virtual CIO services.
Two-factor authentication (2FA) adds a second verification step beyond a password. In SMS-based 2FA, that second factor is typically a one-time code delivered by text message. While this approach remains common, cybersecurity experts increasingly view it as less secure than authenticator apps, passkeys and hardware security keys.
One of the most common forms of 2FA is SMS two-factor authentication (SMS 2FA), where a code is sent to the user’s mobile phone via SMS text to verify their identity. While SMS 2FA is considered a relatively secure form of 2FA, it’s not without its flaws.
Why SMS Two-Factor Authentication Is Vulnerable
SMS 2FA Is Vulnerable to Interception
One of the biggest security flaws with SMS 2FA is the possibility of SMS interception. This occurs when a malicious actor intercepts the SMS message containing the verification code. They then use this code to gain access to the user’s account even if they don’t know the password. This is done through techniques such as SIM swapping where the attacker takes control of the victim’s cell phone number.
SMS 2FA Is Vulnerable to Social Engineering Attacks
Social engineering attacks occur when a hacker tricks the user into giving them their verification code, either through a phone call or an email, by spoofing as a person or representative from an organization that you trust. For example, the cybercriminal might pretend to be from a bank or an online retailer and ask the user to provide their authentication code or one-time password for account security purposes.
Delays in Receiving SMS
Another issue with SMS 2FA is that there can be delays in receiving SMS codes. This is caused by network congestion, problems with the carrier, or other technical issues. The user is then unable to log into their account even if they know their password and are trying to do so from a trusted device.
Many organizations address these risks by adding stronger authentication tools—but the underlying challenge is often broader than a single solution. Security gaps tend to exist across systems, access controls, and user behavior, not just in one authentication method.
Safer Alternatives to SMS 2FA
Given these security flaws, many organizations now recommend authenticator apps, passkeys or hardware security keys instead of SMS 2FA. Because authentication codes are generated on the device rather than transmitted through a mobile carrier, these methods are generally less susceptible to SIM-swapping and SMS interception attacks.
Hardware tokens, such as key fobs, work by generating a unique code that the user enters to log into their account. This eliminates the reliance on the user’s mobile device and reduces the risk of delays in receiving text messages.
2FA Key Takeaways:
- Two-factor authentication requires two different authentication factors for identity verification
- SMS-based two-factor authentication contains several security flaws, including susceptibility to social engineering and the possibility of messages being intercepted
- Limitations of SMS two-factor authentication also includes delays in receiving messages
- Alternative forms of two-factor authentication, like hardware tokens or authenticator apps (e.g. Microsoft authenticator), reduce some risks associated with SMS 2FA
Many organizations don’t realize where their security vulnerabilities exist until they take a closer look at how systems, access controls, and user behavior work together.
At Anders Technology, we help businesses assess their current environment, identify risks across systems, and implement practical strategies to strengthen security—not just at a single point, but across the organization. Learn more about how our clients protect their businesses and assets from evolving cyber threats with our cybersecurity strategies or request a consultation with one of our technology specialists below.