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Security Risks of SMS-Based MFA

Steven Waters
  • Updated

Security Risks of SMS-Based MFA

Understanding the Risks of SMS-Based Multi-Factor Authentication (MFA)

Multi-Factor Authentication (MFA) is an essential security layer that protects Outstaffer platform accounts by requiring a second form of verification in addition to a password. However, not all MFA methods are equally secure. A previously widely used method—SMS-based MFA—has significant vulnerabilities that can leave users at risk of compromise. Below, we explore the key risks associated with SMS-based MFA and why transitioning to more secure alternatives is critical.

The Vulnerabilities of SMS-Based MFA

  1. Interception of SMS Messages: SMS messages are not encrypted. This means attackers can intercept them using techniques like man-in-the-middle (MITM) attacks or by exploiting flaws in mobile network protocols.

  2. SIM Swapping: Attackers can impersonate a victim and convince a mobile service provider to transfer the victim's phone number to a new SIM card. Once the attacker controls the phone number, they can receive SMS-based MFA codes.

  3. Recycled Phone Numbers: Mobile carriers often reassign phone numbers to new users. If an account still relies on an outdated phone number for MFA, the new owner of the number could potentially gain access to that account.

  4. Reliance on Mobile Networks: Outages, poor reception, or changes in phone numbers can prevent users from receiving MFA codes, leading to account lockouts or vulnerabilities.

A Better Approach: Authenticator Apps

To address these risks, we only allow using app-based authenticators like Google Authenticator, Microsoft Authenticator, or Authy. These apps generate time-based one-time passwords (TOTP) that are stored securely on your device and are not vulnerable to interception or SIM-swapping attacks.

Here’s how to set up an authenticator app for MFA:

  1. Download an Authenticator App: Install a trusted app like Google Authenticator or Microsoft Authenticator from your device’s app store.

  2. Enable Authenticator App: Choose the option to set up MFA using an authenticator app. a QR code will typically be displayed.

  3. Scan the QR Code: Open your authenticator app, select “Add Account,” and scan the QR code displayed on your account settings page.

  4. Verify Setup: Enter the verification code generated by your authenticator app into the account settings page to complete the setup.

  5. Backup Codes: Save any backup codes provided during the setup process in a secure location. These can help you regain access if you lose your device.

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