Why you should avoid using one-time passwords sent via text messages

In our digital age, securing online accounts has never been more critical. One-time passwords (OTPs) sent by text message have become a common method for adding an extra layer of security. However, recent developments have shown that this method is fraught with vulnerabilities that can be exploited by cybercriminals. Here’s why you should avoid using OTPs sent by text and consider more secure alternatives.

The Vulnerabilities of SMS OTPs

One-time passwords are designed to be used once and provide a temporary code for logging into websites, authorizing financial transactions, or accessing confidential data. While this may seem secure, the reality is quite different. According to cybersecurity experts, OTPs sent via SMS are susceptible to several types of attacks:

SIM Swap Attacks: In a SIM swap attack, a hacker tricks the mobile carrier into transferring the victim's phone number to a new SIM card. Once the hacker has control of the phone number, they can intercept the OTP sent via text message and gain unauthorized access to the victim's accounts.

Phishing Attacks: Phishing remains one of the most effective methods for cybercriminals. By creating fake login pages, attackers can trick users into entering their OTPs, which are then used to access the victim's accounts.

SMS Interception: The SMS protocol itself is not very secure. Hackers can intercept text messages containing OTPs, especially if the user is connected to an unsecured Wi-Fi network.

Cheryl Winokur Munk highlights, "One-time passwords have become a common method to restore consumer access to apps, but they are vulnerable to hacks". This vulnerability makes SMS OTPs an unreliable method for securing sensitive information.

Real-World Examples of OTP Vulnerabilities

The breach of Twilio, a company that promotes two-factor authentication, is a notable example. Phishers targeted Cloudflare using OTPs issued by Okta, a security company. This incident underscores the need to evaluate the effectiveness of OTPs and consider alternative security measures.

Better Alternatives to SMS OTPs

Given the vulnerabilities of SMS OTPs, it’s crucial to explore more secure authentication methods:

App-Based Multi-Factor Authentication (MFA): Apps like Google Authenticator and Microsoft Authenticator generate OTPs within the app itself, making them less susceptible to interception. These apps use time-based algorithms to generate codes that are valid for a short period, adding an extra layer of security.

Passwordless Authentication: This method removes the password entirely from the authentication process. Instead, it uses cryptographic keys tied to the user’s device and biometrics. This approach significantly reduces the risk of password-based attacks and is considered one of the most secure authentication methods available.

Hardware Tokens: Devices like YubiKey provide a physical form of authentication. These tokens generate OTPs or use cryptographic keys to authenticate the user, making it extremely difficult for attackers to gain access without the physical device.

While one-time passwords sent via text message offer a convenient form of two-factor authentication, they are not without significant risks. From SIM swap attacks to phishing and SMS interception, the vulnerabilities are too substantial to ignore. For a more secure digital experience, consider adopting app-based MFA, passwordless authentication, or hardware tokens. By doing so, you can significantly enhance your account security and protect your sensitive information from cyber threats.