Insights and Resources • Last Updated 7/31/2023

How Secure is Two-Factor Authentication?

If you're worried about protecting your sensitive and personal information, learn how two-factor authentication can help.

By Brian Segal

How secure is two-factor authentication

Two-factor authentication (2FA) is significantly more secure than using just a password. Requiring two forms of authenticating evidence simply makes it more difficult to crack your security system. However, two-factor authentication isn’t hack proof.

So just how secure is two-factor authentication? Is it worth the effort to implement 2FA? Should everyone adopt multi factor authentication? Let’s start with looking at how secure two-factor authentication is.

How Secure is Two-Factor Authentication?

Instances where two-factor authentication has been defeated prompt people to wonder, how secure is two-factor authentication? Two-factor authentication is very secure. No, it’s not perfect. Two-factor authentication can be defeated. But it’s very challenging to bypass good two-factor authentication. Only very skilled and dedicated criminals can defeat 2FA.

So, if you’re using two-factor authentication, you don’t have to run out and pick up a multi-factor authentication solution like an app or buy physical authentication keys. 2FA is quite secure.

If you’d like to beef up your cybersecurity, revising your password security policies will get you much more bang for your buck. Strengthening your passwords is much easier than adding another layer of authentication. And it strengthens your two-factor authentication.

How Two-Factor Improves Security

Imagine a door lock that required two keys to open. Now imagine that one of those keys could only unlock that door lock once and you’d have to have a new key made each time you unlocked the door. That’s similar to how two-factor authentication works.

Most 2FA systems require a username and password—which is one form of authentication—and a single-use code that the user enters after they’ve entered their username and password. That single-use code is the second form of authentication. The three types of authentication are:

  • Something you know - Like a username and password combination
  • Something you have - This is something in your position, like a device
  • Something you are - A biometric, like a fingerprint

Requiring two pieces of authenticating evidence (otherwise known as credentials) makes it much harder to breach your security because a criminal must gain access to both the username and password and the single-use code. If your two-factor authentication is properly implemented, gaining access to both credentials means breaching two devices or systems.

Since passwords get stolen and leaked all the time, having a second layer of security will prevent a lot of breaches and make your security posture much better. But, unfortunately, even a double authentication system isn’t perfectly secure.

Problems Facing 2FA

The overarching theme of the 2FA problems is that two-factor authentication has been around for a long time. So bad actors have had plenty of time to figure out ways to beat two-factor authentication. These methods are related to two weaknesses in 2FA.

First, a two-factor authentication system that uses a password as one form of authentication is using one relatively weak credential. Passwords are frequently exposed in data breaches and leaks. That’s why it’s wise to change your passwords regularly.

The second 2FA problem is that the single-use authentication code must be transmitted to the security system. It’s possible for a bad actor to intercept and read the code as it’s being transmitted to the user’s device.

But remember that a criminal needs to defeat both aspects of 2FA. A bad actor must first gain access to a user’s password. Then the criminal must find out what device is used for 2FA and compromise that device, which has its own safeguards. That’s why two-factor authentication is so much more secure than single-factor authentication.

The bottom line is that while two-factor authentication isn’t unbreakable, it’s far more secure than single-factor authentication and more cost efficient than more complex authentication methods.

Can Two-Factor Authentication be Hacked?

It’s a very strong security protocol. But two-factor authentication can be hacked. A compromised password paired with a compromised device can cause 2FA to fail. But, if you’re careful about your internet activity and use a secure SMS service, the chances of 2FA being hacked are very slim.

The two most common methods of hacking two-factor authentication are man-in-the-middle attacks and SIM swapping.

There are a lot of details involved with these two methods. But the short version is that a criminal must either breach your SMS carrier’s network or convince a cell phone carrier to transfer the victim’s phone number to a new SIM card.

If you have good password security and a quality SMS carrier, it’s very difficult for criminals to defeat your two-factor authentication. In fact, it might be impossible for most criminals, as they won’t have the necessary skills to bypass 2FA and will move on to easier targets.

Best Practices for 2FA

Even though two-factor authentication is quite secure, there are a few best practices for 2FA that you should follow to maximize your cybersecurity posture.

  • Implement strong password policies. Use long passphrases with at least one non-dictionary word and change your passwords every 30 to 90 days.

    The password is the weakest link in your two-factor authentication system. Good password policies will help mitigate this weakness.

  • Use time limited 2FA codes. Single-use codes are good. But codes that expire after a few minutes are even better. That way, unused codes can’t be picked up and used later.

    Also, if the code expires before a criminal is able to compromise the user’s device and read the code, their attack fails. Codes that expire are the most secure.

  • Partner with an SMS carrier that prioritizes security. One of the challenges of two-factor authentication is that you have to rely on a third party network to send 2FA codes. If your SMS carrier’s network is compromised, your two-factor authentication is potentially compromised.

    The best SMS carriers for 2FA are those that operate a private network, with end-to-end encryption.

    A private network minimizes the attack surface. So it’s difficult for cybercriminals to access your carrier’s network at all, let alone breach the network.

    Then, end-to-end encryption protects your 2FA codes if the network is compromised. The codes must be decrypted before a bad actor can use them. With time limited codes, that makes it nearly impossible to crack your two-factor authentication.

    Choosing a quality SMS two-factor authentication provider minimizes the risk of having your security breached because your carrier’s network gets compromised.

Ultimately, two-factor authentication is secure. And with the right policies and best practices, it can be nearly unbreakable.

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