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Setting up delegated Managed Service Accounts

A delegated Managed Service Account (dMSA) is an Active Directory (AD) account that provides secure and efficient management of credentials. Unlike traditional service accounts, dMSAs don't require manual password management since AD automatically takes care of it. With dMSAs, specific permissions can be delegated to access resources in the domain, which reduces security risks and provides better visibility and logs of service account activity.

Setting up a dMSA is currently only available on devices running Windows Server 2025. DMSA is a more secure and manageable approach to service account management compared to traditional service accounts. By migrating critical services to dMSA, organizations can ensure that these services are managed in a secure and compliant manner. DMSA provides a higher level of security by offering unique and frequently rotated passwords, which reduces the likelihood of unauthorized access and improves overall security.

Prerequisites

  • The Active Directory Domain Services role must be installed on your device or on any device if using remote management tools. To learn more, see Install or Uninstall Roles, Role Services, or Features.
  • Once the role is installed, your device must be promoted to a Domain Controller (DC). In Server Manager, the flag icon displays a new notification, select Promote this server to a domain controller, then complete the necessary steps.
  • The KDS root key must be generated on the DC before a dMSA is created or migrated. Run Get-KdsRootKey in PowerShell to verify if the key is available. If the key is unavailable, it can be added by running Add-KdsRootKey –EffectiveTime ((get-date).addhours(-10)).

Note

In order to use the dMSA as a standalone Managed Service Account (MSA) or to supersede a legacy service account, the following command needs to be ran on the client device:

$params = @{
 Path = "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters"
 Name = "DelegatedMSAEnabled"
 Value = 1
 Type = "DWORD"
}
Set-ItemProperty @params

Create a standalone dMSA

The following instructions allow users to create a new dMSA without migrating from a traditional service account.

  1. Open a PowerShell session with admin rights and run:

    $params = @{
 Name = "ServiceAccountName"
 DNSHostName = "DNSHostName"
 CreateDelegatedServiceAccount = $true
 KerberosEncryptionType = "AES256"
}
New-ADServiceAccount @params

  2. Grant permission to the specific device to retrieve the password for the service account in AD:

    $params = @{
 Identity = "DMSA Name"
 PrincipalsAllowedToRetrieveManagedPassword = "Machine$"
}
Set-ADServiceAccount @params

  3. The msDS-DelegatedMSAState property value for the dMSA must be set to 3. To view the current property value, run:

    $params = @{
 Identity = "dMSAsnmp"
 Properties = "msDS-DelegatedMSAState"
}
Get-ADServiceAccount @params

    To set this value to 3, run:

    $params = @{
 Identity = "dMSAsnmp"
 Properties = @{
  "msDS-DelegatedMSAState" = 3
 }
}
Set-ADServiceAccount @params

Migrate to a dMSA

To migrate a service account to a dMSA, follow these steps:

  1. Create a dMSA a described in Create a standalone dMSA.

  2. Initiate account migration to a dMSA:

    $params = @{
 Identity = "<DMSAName>"
 SupersededAccount = "<DN of service account>"
}
Start-ADServiceAccountMigration @params

  3. If the service account being migrated to a dMSA has access to multiple servers, a registry policy must first be applied to ensure it defaults to the DC. Once you sign in using the dMSA, run:

    $params = @{
 Path = "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System\Kerberos\Parameters"
 Name = "DelegatedMSAEnabled"
 Value = "1"
 PropertyType = "DWORD"
 Force = $true
}
New-ItemProperty @params

  4. Once changes to the registry are applied and the account is linked, restart the running services for the account by running:

    Get-Service | Where-Object {$_.Status -eq "Running"} | Restart-Service

Note

In the case that the service account is connected to multiple devices and migration has ended, the PrincipalsAllowedToRetrieveManagedPassword needs to be updated manually.

Complete account migration

Warning

When finalizing the migration, never delete the original service account in case you need to revert back to it post migration as this causes several issues.

To complete the account migration, traditional service accounts must be disabled to ensure that all services use the dMSA.

To disable the traditional service account, run the following command:

$params = @{
 Identity = "<DMSAName>"
 SupersededAccount = "<DN of service account>"
}
Complete-ADServiceAccountMigration @params

If the wrong account is being migrated, run the following to undo all steps during migration:

$params = @{
 Identity = "<DMSAName>"
 SupersededAccount = "<DN of service account>"
}
Undo-ADServiceAccountMigration @params

To revert a service account back to an inactive or unlinked state, run:

$params = @{
 Identity = "<DMSAName>"
 SupersededAccount = "<DN of service account>"
}
Reset-ADServiceAccountMigration @params

View dMSA event logs

Events can be viewed using the Event Viewer (eventvwr.exe) by performing the following actions:

  1. Right-click on Start and select Event Viewer.
  2. In the left pane, expand Applications and Services and navigate to Microsoft\Windows\Security-Kerberos\Operational.
  3. Logging for this provider is disabled by default, to enable logging, right-click on Operational and select Enable Log.

The following table describes these captured events.

Event ID Description
307 dMSA Migration - This event is written for both dMSAs under migration and for ones that migrated. It contains information about the old service account and the new dMSA.
308 dMSA Permission Add - This event is logged when a machine attempts to add itself to the principals allowed to retrieve managed password field of a dMSA during migration.
309 dMSA Key Fetch - This event is logged when the Kerberos client attempts to fetch keys for a dMSA from the domain controller.

See also