Service Accounts

 

Updated: January 29, 2014

Applies To: Windows 7, Windows 8.1, Windows Server 2008 R2, Windows Server 2012 R2, Windows Server 2012, Windows 8

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.

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:

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 Server 2008 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.

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 are an extension of the standalone managed service accounts, which were introduced in Windows Server 2008 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.

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.

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.

System_CAPS_noteNote

Introduced in Windows Server 2008 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 were introduced in Windows Server 2008 R2 and Windows 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 Server 2008 R2, a virtual account that uses the instance name as the service name is established in the format NT SERVICE\<SERVICENAME>.

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

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

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

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