How Long Does an MFA Token Last in Office 365?

"How long does an MFA token last in Office 365?" That’s the burning question on many users' minds today. In a world where digital security is paramount, Multi-Factor Authentication (MFA) has become one of the most important security mechanisms to protect user data. For Office 365 users, it’s particularly critical. But understanding the mechanics of how long an MFA token lasts can be a bit murky.

The length of time an MFA token lasts in Office 365 can significantly impact user experience and security, but it varies depending on several factors, including the specific configurations, user roles, and even the device being used. It's not a straightforward answer because Microsoft provides a range of token lifetimes for different scenarios. Some tokens may last a few hours, while others could persist for several days, depending on the settings and protocols in place.

What is an MFA Token?

Before diving into the specifics, it’s essential to understand what an MFA token is. In simple terms, an MFA token is a temporary digital credential that validates your identity during the authentication process. After you provide your password, you are required to enter a second factor of authentication, such as a one-time passcode (OTP) from an authenticator app or a code sent via SMS. Once the system verifies this second factor, you are granted access, and the MFA token is generated.

The token essentially acts as a key that ensures continuous authentication for a certain period. But this token does expire — and that’s where things get interesting. How long does that key stay valid, and how does Office 365 manage it?

Default Token Lifetimes in Office 365

In Office 365, token lifetimes vary depending on the type of token being used. There are different kinds of tokens, each with their respective lifespan:

1. Access Tokens:
   These are short-lived tokens, typically valid for 1 hour. Access tokens are issued when a user successfully logs into a service or application. The goal here is to ensure that even if an access token gets compromised, it will soon expire.

2. Refresh Tokens:
   Refresh tokens have a much longer lifespan, usually valid for 14 days by default. Their role is to allow a user to maintain access without re-authenticating multiple times throughout the day. If a refresh token remains unused, it will expire after 14 days. However, if you use it regularly (within the sliding window of 90 days), the expiration period extends.

3. Session Tokens:
   These tokens control the user's session and how long they stay signed into Office 365 applications. A session token can remain valid for 90 days under default settings, after which users will be prompted to re-authenticate.

Customizing Token Lifetimes

For most organizations, the default token lifetimes will work fine, but there are scenarios where you might want more control. Microsoft provides the ability to customize the lifetime of these tokens using Azure AD policies. For instance:

• Conditional Access Policies: With conditional access, administrators can enforce stricter policies on certain users or under specific conditions. This could include requiring MFA more frequently based on the user’s location, device, or risk level.
• Token Lifetime Policies: Admins can adjust access token lifetimes to be shorter or longer based on organizational needs. If an enterprise has concerns about security risks, they might opt to reduce token lifetimes to an hour or less. Alternatively, to ease user friction, token lifetimes can be extended.

What Triggers Token Expiration?

Understanding what causes a token to expire is essential for managing user expectations. Token expiration doesn’t only depend on time; several actions or changes in the environment can also prompt an MFA token to expire earlier than expected:

1. Password Reset or Change:
   If a user resets or changes their password, their active tokens are invalidated. The system assumes that a password change might indicate a security event, so users will need to re-authenticate across all devices and services.

2. Device Registration Issues:
   If a user’s device loses its registered status or fails to meet certain security conditions (for example, it becomes non-compliant), the MFA token may expire prematurely, prompting the user to authenticate again.

3. User Risk and Sign-in Behavior:
   Conditional access policies can analyze user behavior and risk levels, such as attempts to log in from unfamiliar locations or devices. If such an event occurs, MFA token validity can be reduced to mitigate risk.

4. Manual Revocation:
   Administrators can manually revoke MFA tokens if they suspect a security breach or for compliance reasons. This action immediately invalidates active tokens, and users will be required to log in again with MFA.

Best Practices for Managing MFA Token Lifetimes

Organizations can strike the right balance between security and user convenience by considering a few best practices when configuring MFA token lifetimes:

• Implement Conditional Access Policies: Tailor token expiration policies based on user roles, devices, and locations. High-risk users or users accessing sensitive data may need to re-authenticate more frequently, while regular users can enjoy more extended sessions.
• Monitor Sign-in Activity: Use Azure AD logs to monitor user sign-ins, failed authentication attempts, and overall token usage. This can give insights into when and why tokens expire prematurely, allowing for better policy adjustments.
• Educate Users: Users often experience frustration when their tokens expire unexpectedly. By educating them on what actions (e.g., password changes) will cause their tokens to expire and how to seamlessly re-authenticate, organizations can minimize disruptions.

The Future of MFA in Office 365

As cybersecurity threats evolve, Microsoft continues to enhance its MFA offering to keep up with both security demands and user experience expectations. One of the most anticipated developments is passwordless authentication. While MFA significantly improves security, the need to remember complex passwords still exists. Passwordless solutions such as biometrics, security keys, or using apps like Microsoft Authenticator aim to simplify the process.

These advancements promise a more seamless experience where tokens may last longer or require less frequent authentication, as the system can continuously verify user identity in the background. Until these technologies are widely adopted, MFA tokens will remain a critical component of Office 365 security.

Conclusion: Balancing Security and User Experience

In Office 365, MFA tokens typically last anywhere from 1 hour for access tokens, to 14 days for refresh tokens, and up to 90 days for session tokens. However, these values can be customized based on security needs or business requirements. Understanding the different types of tokens and the conditions that trigger their expiration can help administrators strike the right balance between ensuring security and maintaining user productivity.

At the end of the day, token lifetimes are all about balance. Shorter lifetimes boost security but at the cost of convenience, while longer lifetimes improve the user experience but might expose you to more risks. As organizations increasingly rely on Office 365, managing token expiration effectively is a critical part of maintaining a secure, smooth user experience.