Group Managed Service Accounts Overview

Applies To: Windows Server (Semi-Annual Channel), Windows Server 2016

This topic for the IT professional introduces the group Managed Service Account by describing practical applications, changes in Microsoft’s implementation, and hardware and software requirements.

Feature description

A standalone Managed Service Account (sMSA) is a managed domain account that provides automatic password management, simplified service principal name (SPN) management and the ability to delegate the management to other administrators. This type of managed service account (MSA) was introduced in Windows Server 2008 R2 and Windows 7.

The group Managed Service Account (gMSA) provides the same functionality within the domain but also extends that functionality over multiple servers. When connecting to a service hosted on a server farm, such as Network Load Balanced solution, the authentication protocols supporting mutual authentication require that all instances of the services use the same principal. When a gMSA is used as service principals, the Windows operating system manages the password for the account instead of relying on the administrator to manage the password.

The Microsoft Key Distribution Service (kdssvc.dll) provides the mechanism to securely obtain the latest key or a specific key with a key identifier for an Active Directory account. The Key Distribution Service shares a secret which is used to create keys for the account. These keys are periodically changed. For a gMSA the domain controller computes the password on the key provided by the Key Distribution Services, in addition to other attributes of the gMSA. Member hosts can obtain the current and preceding password values by contacting a domain controller.

Practical applications

gMSAs provide a single identity solution for services running on a server farm, or on systems behind Network Load Balancer. By providing a gMSA solution, services can be configured for the new gMSA principal and the password management is handled by Windows.

Using a gMSA, services or service administrators do not need to manage password synchronization between service instances. The gMSA supports hosts that are kept offline for an extended time period, and management of member hosts for all instances of a service. This means you can deploy a server farm that supports a single identity to which existing client computers can authenticate without knowing the instance of the service to which they are connecting.

Failover clusters do not support gMSAs. However, services that run on top of the Cluster service can use a gMSA or a sMSA if they are a Windows service, an App pool, a scheduled task, or natively support gMSA or sMSA.

Software requirements

A 64-bit architecture is required to run the Windows PowerShell commands which are used to administer gMSAs.

A managed service account is dependent upon Kerberos supported encryption types.When a client computer authenticates to a server using Kerberos the DC creates a Kerberos service ticket protected with encryption both the DC and server supports. The DC uses the account’s msDS-SupportedEncryptionTypes attribute to determine what encryption the server supports and, if there is no attribute, it assumes the client computer does not support stronger encryption types. If the host is configured to not support RC4, then authentication will always fail. For this reason, AES should always be explicitly configured for MSAs.

Beginning with Windows Server 2008 R2, DES is disabled by default. For more information about supported encryption types, see Changes in Kerberos Authentication.

gMSAs are not applicable to Windows operating systems prior to Windows Server 2012.

Server Manager information

There are no configuration steps necessary to implement MSA and gMSA using Server Manager or the Install-WindowsFeature cmdlet.

See also

The following table provides links to additional resources related to Managed Service Accounts and group Managed Service Accounts.

What’s New for Managed Service Accounts

Applies To: Windows Server (Semi-Annual Channel), Windows Server 2016

This topic for the IT professional describes the changes in functionality for Managed Service Accounts with the introduction of the group Managed Service Account (gMSA) in Windows Server 2012 and Windows 8.

The managed service account is designed to provide services and tasks such as Windows services and IIS application pools to share their own domain accounts, while eliminating the need for an administrator to manually administer passwords for these accounts. It is a managed domain account that provides automatic password management.

What’s new for Managed Service Accounts in Windows Server 2012 and Windows 8

The following describes what changes in functionality were made to MSA in Windows Server 2012 and Windows 8.

Group Managed Service Accounts

When a domain account is configured for a server in a domain, the client computer can authenticate and connect to that service. Previously, only two account types have provided identity without requiring password management. But these account types have limitations:

Computer account is limited to one domain server and the passwords are managed by the computer

Managed Service Account is limited to one domain server and the passwords are managed by the computer.

These accounts cannot be shared across multiple systems. Therefore, you must regularly maintain the account for each service on each system to prevent unwanted password expiration.

What value does this change add?

The group Managed Service Account solves this problem because the account password is managed by Windows Server 2012 domain controllers and can be retrieved by multiple Windows Server 2012 systems. This minimizes the administrative overhead of a service account by allowing Windows to handle password management for these accounts.

What works differently?

On computers running Windows Server 2012 or Windows 8, a group MSA can be created and managed through the Service Control Manager so that numerous instances of the service, such as deployed over a server farm, can be managed from one server. Tools and utilities that you used to administer Managed Service Accounts, such as IIS Application Pool Manager, can be used with group Managed Service Accounts. Domain administrators can delegate service management to service administrators, who can manage the entire lifecycle of a Managed Service Account or the group Managed Service Account. Existing client computers will be able to authenticate to any such service without knowing which service instance they are authenticating to.

Removed or deprecated functionality

For Windows Server 2012 , the Windows PowerShell cmdlets default to managing the group Managed Service Accounts instead of the server Managed Service Accounts.

Service Accounts

Applies to

• Windows 10
• Windows Server 2016

This topic for the IT professional explains group and standalone managed service accounts, and the computer-specific virtual computer account, and it points to resources about these service accounts.

Overview

A service account is a user account that is created explicitly to provide a security context for services running on Windows Server operating systems. The security context determines the service’s ability to access local and network resources. The Windows operating systems rely on services to run various features. These services can be configured through the applications, the Services snap-in, or Task Manager, or by using Windows PowerShell.

This topic contains information about the following types of service accounts:

Standalone managed service accounts

A managed service account is designed to isolate domain accounts in crucial applications, such as Internet Information Services (IIS), and eliminate the need for an administrator to manually administer the service principal name (SPN) and credentials for the accounts.

To use managed service accounts, the server on which the application or service is installed must be running at least Windows ServerВ 2008В R2. One managed service account can be used for services on a single computer. Managed service accounts cannot be shared between multiple computers, and they cannot be used in server clusters where a service is replicated on multiple cluster nodes. For this scenario, you must use a group managed service account. For more information, see Group Managed Service Accounts Overview.

In addition to the enhanced security that is provided by having individual accounts for critical services, there are four important administrative benefits associated with managed service accounts:

You can create a class of domain accounts that can be used to manage and maintain services on local computers.

Unlike domain accounts in which administrators must reset manually passwords, the network passwords for these accounts are automatically reset.

You do not have to complete complex SPN management tasks to use managed service accounts.

Administrative tasks for managed service accounts can be delegated to non-administrators.

Software requirements

Managed service accounts apply to the Windows operating systems that are designated in the Applies To list at the beginning of this topic.

Group managed service accounts

Group managed service accounts are an extension of the standalone managed service accounts, which were introduced in Windows ServerВ 2008В R2. These are managed domain accounts that provide automatic password management and simplified service principal name (SPN) management, including delegation of management to other administrators.

The group managed service account provides the same functionality as a standalone managed service account within the domain, but it extends that functionality over multiple servers. When connecting to a service that is hosted on a server farm, such as Network Load Balancing, the authentication protocols that support mutual authentication require all instances of the services to use the same principal. When group managed service accounts are used as service principals, the Windows Server operating system manages the password for the account instead of relying on the administrator to manage the password.

The Microsoft Key Distribution Service (kdssvc.dll) provides the mechanism to securely obtain the latest key or a specific key with a key identifier for an Active Directory account. This service was introduced in Windows Server 2012, and it does not run on previous versions of the Windows Server operating system. The Key Distribution Service shares a secret, which is used to create keys for the account. These keys are periodically changed. For a group managed service account, the domain controller computes the password on the key that is provided by the Key Distribution Services, in addition to other attributes of the group managed service account.

Practical applications

Group managed service accounts provide a single identity solution for services running on a server farm, or on systems that use Network Load Balancing. By providing a group managed service account solution, services can be configured for the group managed service account principal, and the password management is handled by the operating system.

By using a group managed service account, services or service administrators do not need to manage password synchronization between service instances. The group managed service account supports hosts that are kept offline for an extended time period and the management of member hosts for all instances of a service. This means that you can deploy a server farm that supports a single identity to which existing client computers can authenticate without knowing the instance of the service to which they are connecting.

Failover clusters do not support group managed service account s. However, services that run on top of the Cluster service can use a group managed service account or a standalone managed service account if they are a Windows service, an App pool, a scheduled task, or if they natively support group managed service account or standalone managed service accounts.

Software requirements

Group managed service accounts can only be configured and administered on computers running at least Windows Server 2012, but they can be deployed as a single service identity solution in domains that still have domain controllers running operating systems earlier than Windows Server 2012. There are no domain or forest functional level requirements.

A 64-bit architecture is required to run the Windows PowerShell commands that are used to administer group managed service accounts.

A managed service account is dependent on encryption types supported by Kerberos. When a client computer authenticates to a server by using Kerberos protocol, the domain controller creates a Kerberos service ticket that is protected with encryption that the domain controller and the server support. The domain controller uses the account’s msDS-SupportedEncryptionTypes attribute to determine what encryption the server supports, and if there is no attribute, it assumes that the client computer does not support stronger encryption types. The Advanced Encryption Standard (AES) should always be explicitly configured for managed service accounts. If computers that host the managed service account are configured to not support RC4, authentication will always fail.

NoteВ В Introduced in WindowsВ ServerВ 2008В R2, the Data Encryption Standard (DES) is disabled by default. For more information about supported encryption types, see Changes in Kerberos Authentication.

Group managed service accounts are not applicable in Windows operating systems prior to Windows Server 2012.

Virtual accounts

Virtual accounts were introduced in Windows ServerВ 2008В R2 and WindowsВ 7, and are managed local accounts that provide the following features to simplify service administration:

The virtual account is automatically managed.

The virtual account can access the network in a domain environment.

No password management is required. For example, if the default value is used for the service accounts during SQL Server setup on Windows ServerВ 2008В R2, a virtual account that uses the instance name as the service name is established in the format NT SERVICE\ .

Services that run as virtual accounts access network resources by using the credentials of the computer account in the format \ $.

For information about how to configure and use virtual service accounts, see Service Accounts Step-by-Step Guide.

Software requirements

Virtual accounts apply to the Windows operating systems that are designated in the Applies To list at the beginning of this topic.

See also

The following table provides links to additional resources that are related to standalone managed service accounts, group managed service accounts, and virtual accounts.