Microsoft Authenticator for passwordless login

 

The trend of abandoning traditional passwords is already a reality in the Microsoft ecosystem, and Microsoft Authenticator has become the key to achieving this easily and securely. If you're tired of remembering passwords, changing them frequently, or worrying about data breaches, this passwordless system is probably what you've been looking for.

With Microsoft Authenticator, you can sign in to your personal, work, and school accounts using just your mobile device and a quick gesture: a PIN, fingerprint, or facial recognition. Behind this seemingly simple process lies an advanced authentication system based on keys and credentials linked to the device, designed to reduce the risk of credential theft and phishing attacks.

What is Microsoft Authenticator and how does passwordless sign-in work?

Microsoft Authenticator is a free mobile app available for iOS and Android that centralizes secure access to your Microsoft accounts and many other compatible accounts. It doesn't just display codes; it lets you use your mobile device as a "key" to log in to your services without typing a password.

The passwordless mode works using public key authentication (see how to activate and use passkeys ): a credential is generated and associated with your account, cryptographically linked to the device where the app is installed. This credential can only be unlocked with a local gesture (PIN, fingerprint, face) thanks to the operating system's own security mechanisms.

This approach is very similar to that used by Windows Hello with FIDO2 keys for businesses, where the computer acts as a trusted device and the user authenticates with biometrics or a PIN. The key difference is that Authenticator can be used virtually anywhere, not just on your PC, as it's designed for iOS and Android mobile devices.

When you use passwordless sign-in with Microsoft Authenticator, the typical process is that the service displays a number on your screen , and on your phone, the app prompts you to tap that same number to confirm your identity. It doesn't ask for your username or password on your mobile device, only that code and then your local unlock method.

Ways to use Microsoft Authenticator

Microsoft Authenticator can perform three different functions depending on how you have it configured and what you need for each service, so you are not limited to a single mode.

First, you can use the app as a backup when you forget your password . In this case, it allows you to approve a notification or enter a temporary code that lets you regain access to your account if you don't remember your password or need to prove you are the rightful owner.

The second way to use it is as a two-step verification method or MFA ( multi-factor authentication ). Here you still enter your password, but you add a second layer of security with a unique code or a push notification that you must approve on your mobile device, making it much harder for an attacker to gain access using only your password.

The third scenario, and the one we're interested in for this article, is using Authenticator as the sole login method . In this mode, you completely forgo the password, and the entire process relies on the notification you receive on your mobile device and local verification via PIN or biometrics.

Advantages of stopping the use of passwords

Eliminating passwords offers clear benefits to both users and organizations . Beyond convenience, the goal is to reduce the attack vectors associated with the use of static passwords.

On the one hand, no longer writing down passwords means you're no longer vulnerable to phishing attacks , keyloggers, or the reuse of leaked passwords on other services. If there's no password for you to enter, there's nothing to steal from a fake login form.

From a user experience perspective, access is much faster and more natural : you unlock your phone with your usual method, confirm a notification, and you're done. You don't have to invent complicated passwords or remember absurd variations just to meet length and complexity requirements.

Businesses also benefit, as the number of support requests related to password resets, account lockouts, and authentication issues decreases. Security improves without users feeling constantly hampered by the system.

In addition, Microsoft Authenticator and methods such as Windows Hello, physical security keys, and SMS codes provide alternative mechanisms for different use cases. Although Microsoft and many organizations recommend using passkeys and passwordless authentication, complementary options still exist when using a mobile device is not possible, and details are also provided on how to use a mobile device as a FIDO2 authenticator.

Compatibility, supported accounts, and multi-account usage

Microsoft Authenticator works natively on iOS and Android devices , with updated operating system versions to take advantage of the latest security enhancements. It's important to keep both your phone and the app up to date with the latest updates.

Regarding the accounts it supports, you can use Authenticator with your personal Microsoft account , Microsoft Entra ID (formerly Azure AD) work or school accounts, and other accounts that support the same standards. This ranges from a typical Outlook email to organizations using Microsoft 365.

One of the great advantages is that you can set up multiple accounts on the same device and, if you wish, even turn your Android into a security key to improve the authentication experience on Windows.

Regarding the accounts it supports, you can use Authenticator with your personal Microsoft account , Microsoft Entra ID (formerly Azure AD) work or school accounts, and other accounts that support the same standards. This ranges from typical Outlook email to organizations using Microsoft 365.

For Microsoft Entra ID users, such as consultants or students working with multiple organizations, it's possible to add multiple accounts from the same tenant or different tenants to Authenticator and enable passwordless mode for all of them. However, guest accounts are not supported for passwordless phone sign-in from the same device.

It's important to remember that each device you want to use for passwordless login must be registered with its corresponding tenant. For example, if you work with contoso.com and wingtiptoys.com, the same mobile device will need to be registered in both environments to authenticate the associated accounts.

Prerequisites for using Microsoft Authenticator without a password

Before getting started with passwordless mode, there are a number of conditions that must be met , both by the user and the organization's administrators.

In corporate environments, it is recommended to use Microsoft Multi-Factor Authentication (MFA) with push notifications enabled as one of the verification methods. These notifications help prevent unauthorized access and stop potential fraudulent transactions, as the user must approve each login attempt ( two-step verification ).

The Authenticator app, in addition to managing notifications, can generate temporary security codes even without an internet connection. This way, even if the phone has no data or Wi-Fi, the user still has a backup login method when a code is requested.

To use passwordless authentication in Microsoft Entra ID, the administrator must enable the combined sign-in experience (where the user configures security methods) and then explicitly activate the passwordless method for the desired groups or users.

For personal Microsoft accounts, the basic requirement is to have installed Microsoft Authenticator (or, in some scenarios, Outlook for Android) on a compatible device and follow the guided process to activate passwordless sign-in from the account settings.

Configure Microsoft Authenticator as a passwordless login method

In organizations using Microsoft Entra ID, administrators have an authentication methods policy that defines which methods users can use to log in: passwords, Authenticator, FIDO2 keys, SMS, etc. For deployment and management plans, see how to integrate Windows Hello with FIDO2 keys.

Within that policy, you can enable Microsoft Authenticator for both traditional MFA notifications and passwordless phone sign-in. Once enabled, the user will see Microsoft Authenticator as an available method in the Security Information section of their account.

Depending on the administrator's settings, the configuration interface will display something like Microsoft Authenticator – No Password or Microsoft Authenticator – MFA Insertion . The user can register the application and choose the mode that best suits their organization's policies.

To enable the passwordless phone sign-in method from the administrator's perspective, you need to sign in to the Microsoft Sign In admin center with an appropriate role (for example, authentication policy administrator) and navigate to the Sign In ID > Authentication methods > Policies section.

By default, each group is enabled to use any mode of the selected method. In the case of Authenticator, the "any" option allows both push notifications and passwordless phone login, and the administrator can adjust which groups or users are included or excluded.

User registration in the Authenticator application

Once the method is activated within the organization, it's time for users to register the application to their account . Those already using Authenticator for MFA usually have it easier, as they only need to add the passwordless mode.

Users who have not yet configured Authenticator can opt for direct telephone login registration , without needing to use a password at any time, provided they have a temporary access pass provided by the administrator or organization.

In this straightforward process, the user obtains the temporary access pass, installs the app on their mobile device, selects "Add account" within Microsoft Authenticator, and chooses "Work or school account." Then, they tap "Sign in" and enter the temporary pass when prompted, following the instructions to complete the setup.

Another option is to use a guided process from the Security Information page (sometimes called My Sign-Ins). The user accesses this page from a browser, logs in with their current method, and chooses “Add Method” > “Authenticator Application” > “Add”.

The assistant will guide you through the steps to install and link the app to your account: scan a QR code, approve a notification, and complete the setup. Once this is done, the user taps "Done," and the account is registered on their mobile device.

Enable passwordless phone login

After registering the account in Microsoft Authenticator, there is still one step left: enabling passwordless mode for that specific account within the mobile application itself.

To do this, the user opens Microsoft Authenticator, selects the account in question, and clicks on the option " Set up passwordless sign-in requests " or something similar. From there, they follow the on-screen instructions, which usually include approving a test request and verifying using a PIN or biometrics.

Once this process is complete, that account is ready to receive passwordless login requests , and the user can choose that method on the Microsoft login screen when needed.

How to sign in without a password using Microsoft Authenticator

Once everything is set up, the login process differs slightly from the classic password-based workflow, but it remains very intuitive and quick . The user enters their email address or account name in the login panel as usual.

After clicking “Next”, the system may directly display the option to use the app, or you may need to select “ Other ways to sign in ” to see all available alternatives, depending on the settings and the last method used.

Among these options will appear “ Approve a request in my Authenticator app ”. When you select it, the screen will display a random number and, within seconds, your mobile device will receive a notification from Microsoft Authenticator with that same number for you to confirm.

Instead of typing a password, the user taps the correct number in the app and then validates it with the local unlock method (PIN, fingerprint, facial recognition, depending on the device settings). If everything is correct, the login is complete.

Once the user has authenticated in this way, the platform will tend to prioritize the passwordless method the next time , although the option to choose another method, for example, "Use password instead" is usually available if for some reason the user prefers it.

Use of temporary access passes for the first login

In some organizations, the administrator enables temporary access passes so that users can configure Authenticator and passwordless mode without having to remember an initial password or during bulk onboarding processes.

In these cases, the user opens a browser (on their mobile device or computer) and goes to the Security Information page, where they register the Authenticator app as their login method using the temporary passcode. This action securely links the account to the application.

After pairing the app, the user returns to their mobile device, opens Authenticator, and enables passwordless login for that account. From that moment on, they can log in using their phone without needing a traditional password.

Security, risks, and best practices when using Authenticator

Passwordless authentication with Authenticator is, by design, more secure than relying on a key that can be stolen, leaked, or guessed. However, like any system, it also has its own threat model, and it's important to understand it well.

One of the most concerning aspects is that the iOS and Android apps rely on the same PIN or device unlock method . Currently, there isn't a separate PIN specifically for the app. This means that if someone sees your PIN and steals your phone, they could open the app.

Given this scenario, there are several recommended measures: use a complex PIN or biometrics that are difficult to replicate, activate device erasure options after several failed attempts, and above all, act quickly to revoke the app if you lose your phone or it is stolen, by accessing your account panel from another device.

Another logical concern is that, with access to the app, an attacker could approve login notifications without your knowledge. That's why it's crucial to monitor the notifications you receive, check the location and application from which they are being used, and not accept requests you don't recognize.

If you lose your phone or replace it with another one, it's a good practice to go to your Microsoft account dashboard, navigate to advanced security options, and remove any authentication methods associated with the old device, such as "Send sign-in notification," "App: Microsoft Outlook," or Microsoft Authenticator, to prevent them from remaining valid.

Authenticator management and administration in organizations

In corporate environments, the most recommended way to manage the use of Microsoft Authenticator is through the authentication methods policy in Microsoft Entra ID. This centralized policy allows administrators to control which methods are allowed, for which groups, and under what conditions.

Administrators can fully enable or disable Authenticator , include or exclude specific users and groups, and also adjust parameters that add context to login requests so that the user does not approve anything "blindly".

For example, the organization can configure each notification to display the approximate location of the login attempt or the name of the application requesting access. This way, the user immediately notices if an unfamiliar country or app appears.

It is worth noting that the old directive inherited AuthenticatorAppSignInPolicy no longer supported with modern Authenticator configurations for notifications and passwordless mode. Instead, management should be done exclusively through the Authentication Methods policy.

In scenarios with hybrid or federated users (for example, when using Active Directory Federation Services), the moment a user enables any credential without password, the login process no longer relies on login_hint to send it directly to the federated identity provider, which slightly changes the login experience.

Common problems and known limitations

Like any technology deployed on a large scale, the passwordless login system with Authenticator has some known problems and cases that are worth knowing about beforehand to avoid surprises.

One of the most common scenarios is that the user doesn't see the option to log in by phone without a password on the login screen, even after completing registration. Sometimes this happens because there's a pending verification process that hasn't been fully completed.

To resolve this, simply open the Authenticator app on your phone and respond to any pending notifications. Once you've done this, the option to use your phone without a password should reappear on subsequent login attempts.

In organizations where the administrator has configured conditional access policies, you might see messages such as " You may be logging in from a location restricted by your administrator " or the app might instruct you to go to aka.ms/mfasetup to complete the setup. This indicates that corporate policy is blocking the registration or use of Authenticator.

In these cases, there's not much you can do on your own: you'll need to contact the administrator to enable the passwordless phone login method for your work or school account, or to tell you the correct registration procedure.

There is also a limitation related to local users or many devices . A user can create and use a phone login credential without a password, but if they try to update too many installations (for example, more than five different mobile devices) with that same credential, the operation may fail and it will be necessary to clean up old records.

For those concerned about the risk of mobile phone theft, it's worth remembering that, even with that risk, passwordless methods based on biometrics, security keys, or applications like Authenticator are generally more robust than classic passwords , which can be leaked en masse or guessed through automated attacks.

Thanks to the combination of device-linked credentials , local factors (PIN, fingerprint, face), and administrative control through Microsoft Entra policies, the Microsoft Authenticator ecosystem offers a fairly solid balance between convenience and security, provided that good practices are applied and there is a quick response to device loss or theft.

Adopting passwordless login with Microsoft Authenticator represents a significant shift in mindset , but once configured and understood, it becomes a very convenient and secure way to access your accounts, avoiding the burden of remembering passwords and simultaneously reducing the attack surface against impersonation and unauthorized access.