What is Two-Factor Authentication (2FA)?

​​​​​​Two-factor authentication (2FA) is a specific type of ​​​​​​multi-factor authentication (MFA) that strengthens organizational security by requiring two different methods (also referred to as authentication factors) to verify user identity. If you’ve ever received a text message or e-mail code when logging in, asking you to confirm your identity — that’s 2FA at work. ​ 

In in today’s digital world, every account is protected by a digital door; users’ most valuable digital assets — their data, apps, and systems access — are kept behind it. For decades, usernames and passwords served as the sole keys to those doors. This one-step security protocol is known as “single-factor authentication.”  

Over time, those passwords got reused and simplified as users wrestled to connect with a blossoming number of online accounts. At the same time, improved hacking tools and attacker skills made single-factor authentication easier than ever to compromise. With advanced techniques, attackers can now steal, guess, or circumvent weak passwords all without the user ever realizing someone is accessing their account. The solution? Adding extra layers of protection  

​​​​​Think of 2FA as a second lock added to the door securing online accounts, one that requires a separate and distinctly different kind of key. Verifying identity using a second factor makes it exponentially more difficult for anyone but the authorized user to log in, even if an attacker knows the original  password. 

2FA is also plays a critical role in a zero-trust security model, ensuring that even if one layer of credentials is compromised, an additional layer of verification still prevents unauthorized access. 2FA is an effective way to protect data and systems against many security threats that target user passwords and accounts, such as phishing, brute-force attacks, credential exploitation, and more. 

Two-factor authentication (2FA) is a security methodology that requires users to provide two different authentication factors before gaining access to a system, account, application, network, or data store. The first authentication factor is typically the standard username and password combination. The second factor falls into one of three categories:

• Something you know: This knowledge-based factor relies on something the user knows, such as a secondary password, PIN, or personal security questions.

• Something you have: This method verifies identity through a physical item the user possesses, such a mobile phone, a security token, or a smart card. The item either generates or receives a one-time password (OTP) or serves as a physical key.

• Something you are: Biometric authentication types, such as fingerprints, iris and retina scans, voice and facial recognition, and more can be used to physically verify a user’s identity.

What is the goal of 2FA?

The goal of 2FA is to enhance the security of user accounts, systems, and data by requiring two separate forms of verification before granting access. 2FA goes beyond simple username and password protection and makes it much more difficult for unauthorized individuals to access sensitive information and critical systems.

Not only can 2FA prevent unauthorized access, it also helps mitigate the impact of compromised credentials, aids in compliance with regulatory compliance, and enhances overall trust and confidence in the organization’s security posture.

Multi-factor authentication (MFA) is a broader security approach that requires two or more factors to verify a user’s identity. 2FA is a subset of MFA that requires exactly two distinct factors.

For example, after entering a username and password (the first factor), 2FA requires one additional step, like a fingerprint scan or a passcode sent by text or displayed on a hardware token. While 2FA involves just two steps, MFA often requires additional steps for added layers of account and systems security in keeping with their criticality and risk profile.

Enabling two-factor authentication (2FA) adds an extra layer of security to your accounts by requiring users to provide two forms of identification before gaining access.

Here's a general guide on how you may enable 2FA for a user account:

1. Choose a 2FA method – Identify the 2FA method you want to use. Common options include text messages (SMS), authenticator apps, hardware tokens, or biometric verification.

2. Go to Account Settings – Log in to the account for which you want to enable 2FA. Navigate to the account settings or security settings section. This is usually found in the user profile or security preferences.

3. Locate two-factor authentication – Look for the section related to two-factor authentication or security settings. The exact wording may vary depending on the service.

4. Select 2FA method – Choose the 2FA method you prefer. If you're using SMS, you'll likely need to enter your phone number. For authenticator apps, you may need to scan a QR code provided by the service.

5. Verify your identity – Follow the instructions to verify your identity. This may involve entering a code sent to your phone via SMS, confirming a code from an authenticator app, or using another verification method.

6. Save the backup codes (optional) – Some services provide backup codes that you can use if you're unable to access your primary 2FA method. It's advisable to save these codes in a secure location.

7. Complete the setup – Complete the setup process as instructed by the service. Once done, 2FA will be enabled for your account.

2FA Made Easy With Duo

Duo’s 2FA solution only requires users to carry one device — their smartphone, with the Duo Mobile app installed on it. Duo Mobile is available for both iPhones and Android, as well as wearables like the Apple Watch.

With support for a large array of authentication methods, logging in via push notification is fast and easy with Duo Mobile. We strongly recommend using Duo Push or WebAuthn as a second factor, as they're the most secure and can protect against adversary-in-the-middle (AiTM) attacks. With Duo's flexibility and customizability, however, organizations can find the method that meets the unique needs of a diverse user base.

Yes! 2FA is generally considered a safe and effective security measure.

While 2FA is generally secure, it's important to note that no security measure is completely foolproof. Here are a few challenges to consider:

• What if a user loses their mobile device?

  • Some 2FA factors rely on users to have a device with which to authenticate. If that smartphone or laptop is lost or stolen, there’s a heightened risk that unauthorized entities will be able to access sensitive data. So, users should always be aware of their devices’ locations and cautious about letting others use them.

• Can I limit access to some applications but not others?

  • With a good adaptive authentication solution, yes! And as the security industry evolves, it becomes ever more important to practice least privilege access. Remember, the goal of a security policy is to limit access to as few users as possible — a concept that applies at the application level, as well. To truly reduce the possibility of a breach, each user should be able to authenticate to only the applications their role requires, and their level of access should be based on the information they need to perform their jobs.

• How does 2FA work when users are traveling?

  • In most cases, 2FA should work exactly the same way when users are traveling as it would when they’re at home. And with Duo Mobile, it does. Users enter a password, validate the login attempt via push notification, and hit accept. Even when in airplane mode or otherwise without a cellular or Wi-Fi Internet connection, the Duo Mobile app can generate a valid passcode to act as a second factor.

The need for 2FA has increased as companies, governments, and the public realize that passwords alone are not enough to protect accounts and data in today’s high-risk digital landscape. 2FA enhances the security of online accounts and systems through:

• Protection against password theft – Since 2FA requires an additional factor (such as a temporary code sent to a mobile device), even if a password is compromised, it's not enough for an attacker to gain unauthorized access.

• Mitigation of phishing attacks – phishing attacks often involve tricking users into revealing their passwords. With 2FA, even if a user falls victim to a phishing attack and provides their password, the attacker would still need the second factor to access the account.

• Flexibility in implementation – 2FA can be implemented using various methods, such as one-time codes, biometrics, or hardware tokens. Organizations can choose the method that best suits their preferences and security needs.

• Compliance with security standards – Using 2FA helps organizations comply with regulatory standards and industry best practices.

There are a number of second factors that can be used to verify user identity. From passcodes to biometrics, the available options address a range of use cases and protection levels. These include:

• SMS 2FA – SMS two-factor authentication validates the identity of a user by texting a security code to a mobile device. The user then enters the code into the website or application to which they're authenticating.

• TOTP 2FA – The Time-Based One Time Password (TOTP) 2FA method generates a key locally on the device a user is attempting to access. The security key is generally a QR code that the user scans with a mobile device to generate a series of numbers. The user then enters those numbers into the website or application to gain access. The passcodes expire after a short period, and new ones will be generated the next time a user logs in to the account.

• Push-based 2FA – Push-based 2FA improves on SMS and TOTP 2FA by adding additional layers of security, while improving ease of use for users. Push-based 2FA solutions like Duo Push confirm a user's identity by serving up a push notification on their chosen device with an “approve” button that users can simply click to gain access.

• WebAuthn – Created by the Fast IDentity Online (FIDO) Alliance and the World Wide Web Consortium (W3C), the browser-based WebAuthn API lets Web apps create strong, public-key cryptographic credentials for registration and authentication, obviating the need for passkeys and tokens. Used mostly in conjunction with biometric authentication, WebAuthn is playing a key role in the infosec industry effort to eliminate traditional passwords altogether.