Recommend secure authentication and security authorization strategies

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Choosing the correct authentication method is the first concern for organizations wanting to move their apps to the cloud. Don't take this decision lightly for the following reasons:

  • It's the first decision for an organization that wants to move to the cloud.
  • The authentication method is a critical component of an organization's presence in the cloud. It controls access to all cloud data and resources.
  • It's the foundation of all the other advanced security and user experience features in Azure AD.

Identity is the new control plane of IT security, so authentication is an organization's access to the new cloud world. Organizations need an identity control plane that strengthens their security and keeps their cloud apps safe from intruders.

Secure Authentication methods

When the Azure AD hybrid identity solution is your new control plane, authentication is the foundation of cloud access. Choosing the correct authentication method is a crucial first decision in setting up an Azure AD hybrid identity solution. Implement the authentication method configured by using Azure AD Connect, which also provisions users in the cloud.

To choose an authentication method, consider the time, existing infrastructure, complexity, and cost of implementing your choice. These factors are different for every organization and might change over time.

Azure AD supports the following authentication methods for hybrid identity solutions.

Cloud authentication

When choosing this authentication method, Azure AD handles users' sign-in process. Cloud authentication includes single sign-on (SSO), so that users can sign into cloud apps without re-entering their credentials. With cloud authentication, there are two options:

Azure AD password hash synchronization

The simplest way to enable authentication for on-premises directory objects in Azure AD. Users can use the same username and password that they use on-premises without deploying any additional infrastructure. Some premium features of Azure AD, like Identity Protection and Azure AD Domain Services, require password hash synchronization, no matter which authentication method is chosen.

Azure AD Pass-through Authentication

Azure AD Pass-through Authentication provides a simple password validation for Azure AD authentication services by using a software agent that runs on one or more on-premises servers. The servers validate the users directly with your on-premises Active Directory, ensuring that the password validation doesn't happen in the cloud.

Companies with a security requirement to immediately enforce on-premises user account states, password policies, and sign-in hours might use this authentication method. For more information on the actual pass-through authentication process, see User sign-in with Azure AD pass-through authentication.

Federated authentication

Azure AD hands off the authentication process to a separate trusted authentication system when you choose this authentication method. An example is on-premises Active Directory Federation Services (AD FS) to validate the user's password.

The authentication system can provide additional advanced authentication requirements. Examples are smartcard-based authentication or third-party multifactor authentication. For more information, see Deploying Active Directory Federation Services.

The following section helps determine which authentication method is right using a decision tree. It helps determine whether to deploy a cloud or federated authentication for an Azure AD hybrid identity solution.

Architecture diagrams

The following diagrams outline the high-level architecture components required for each authentication method that can be used with an Azure AD hybrid identity solution.

The simplicity of a password hash synchronization solution:

Diagram showing Azure A D hybrid identity with Password hash synchronization.

Agent requirements of pass-through authentication, using two agents for redundancy:

Diagram showing Azure A D hybrid identity with Pass-through Authentication.

Components required for federation in your perimeter and internal network of your organization:

Diagram showing Azure A D hybrid identity with federated authentication.

Comparing Authentication Methods

The following table offers a detailed comparison of the various authentication methods available and their respective features.

Consideration Password hash synchronization + Seamless SSO Pass-through Authentication + Seamless SSO Federation with AD FS
Where does authentication happen? In the cloud In the cloud, after a secure password verification exchange with the on-premises authentication agent On-premises
What are the on-premises server requirements beyond the provisioning system: Azure AD Connect? None One server for each additional authentication agent Two or more AD FS servers
Two or more WAP servers in the perimeter/DMZ network
What are the requirements for on-premises Internet and networking beyond the provisioning system? None Outbound Internet access from the servers running authentication agents Inbound Internet access to WAP servers in the perimeter
Inbound network access to AD FS servers from WAP servers in the perimeter
Network load balancing
Is there a TLS/SSL certificate requirement? No No Yes
Is there a health monitoring solution? Not required Agent status provided by Azure Active Directory admin center Azure AD Connect Health
Do users get single sign-on to cloud resources from domain-joined devices within the company network? Yes with Seamless SSO Yes with Seamless SSO Yes
What sign-in types are supported? UserPrincipalName + password UserPrincipalName + password UserPrincipalName + password
Windows-Integrated Authentication by using Seamless SSO Windows-Integrated Authentication by using Seamless SSO sAMAccountName + password
Alternate login ID Alternate login ID Windows-Integrated Authentication
Certificate and smart card authentication
Alternate login ID
Is Windows Hello for Business supported? Key trust model Key trust model Key trust model
Requires Windows Server 2016 Domain functional level
Certificate trust model
What are the multifactor authentication options? Azure AD Multi-Factor Authentication Azure AD Multi-Factor Authentication Azure AD Multi-Factor Authentication
Custom Controls with Conditional Access* Custom Controls with Conditional Access* Azure AD Multi-Factor Authentication server
Third-party MFA
Custom Controls with Conditional Access*
What user account states are supported? Disabled accounts Disabled accounts Disabled accounts
Account locked out Account locked out
Account expired Account expired
Password expired Password expired
Sign-in hours Sign-in hours
What are the Conditional Access options? Azure AD Conditional Access, with Azure AD Premium Azure AD Conditional Access, with Azure AD Premium Azure AD Conditional Access, with Azure AD Premium
AD FS claim rules
Is blocking legacy protocols supported? Yes Yes Yes
Can logo, image, and description be customized on the sign-in pages? Yes, with Azure AD Premium Yes, with Azure AD Premium Yes
What advanced scenarios are supported? Smart password lockout Smart password lockout Multisite low-latency authentication system
Leaked credentials reports, with Azure AD Premium P2 AD FS extranet lockout
Integration with third-party identity systems

Secure Authorization Methods

Authorization verifies that the identity attempting to connect has the necessary permissions to access a service, feature, function, object, or method. Authorization always occurs after successful authentication. If a connection isn't authenticated, it fails before any authorization checking is performed. If authentication of a connection succeeds, a specific action might still be disallowed because the user or group did not have the authorization to perform that action.

Administrators benefit from understanding the following authorization methods to enforce Zero Trust. To learn more about these authorization methods, see Get started with permissions, access, and security groups.

Authorization Methods

  • Security group membership
  • Role-based access control
  • Access levels
  • Feature flags
  • Security namespaces & permissions