IT Toolbox
Procedure

Create a gMSA for a Windows service

Create a group Managed Service Account for a Windows service, restrict which hosts can retrieve its managed password, install and test the account on a pilot server, and migrate the service with a rollback path.

Active Directory

Objective

Create a group Managed Service Account for a Windows service, restrict which hosts can retrieve its managed password, install and test the account on a pilot server, and migrate the service with a rollback path.

Prerequisites

  • Known domain topology, administrative boundaries and privileged access method.
  • Current DNS, time synchronization and replication health for identity-related procedures.
  • Administrative access appropriate to the system being changed or diagnosed.
  • A clearly identified scope: affected users, systems, addresses, services and the time of the observed problem.
  • A maintenance or test window when the procedure can affect production traffic or availability.
  • A copy of the current configuration or other recovery material before any irreversible action.

Step-by-step procedure

1

Establish the baseline and scope

Before changing anything, reproduce the issue or document the requested change on a representative system. Record the affected users or services, exact time, current configuration, recent changes and a known-good comparison point. This baseline is the reference used to decide whether each later step improves the situation.

Expected result
  • The scope and current state are documented well enough to reproduce or verify the procedure.
2

A rollback path

Implement this requirement in a controlled scope: a rollback path. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Expected result
  • Evidence for this area is explicit, reproducible and consistent with the intended design.
3

Current configuration and dependencies

Implement this requirement in a controlled scope: current configuration and dependencies. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Expected result
  • Evidence for this area is explicit, reproducible and consistent with the intended design.
4

Controlled validation

Implement this requirement in a controlled scope: controlled validation. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Expected result
  • Evidence for this area is explicit, reproducible and consistent with the intended design.
5

Rollback readiness

Implement this requirement in a controlled scope: rollback readiness. Capture the previous value or configuration first, make the smallest change that satisfies the design, and validate the effective state rather than assuming that a saved setting is active. If the expected result is not obtained, stop, restore the previous state, and reassess before expanding the change.

Expected result
  • Evidence for this area is explicit, reproducible and consistent with the intended design.
6

Validate the complete service

Repeat the original user, system or application workflow from the real source and verify the complete result, not only one command or one local check. Confirm that logs and monitoring show the expected behavior and that no temporary debug, bypass, test account, rule or maintenance setting remains enabled.

Expected result
  • The end-to-end service works or the remaining failure is isolated to a clearly identified component.

Technical commands from the original procedure

These technical blocks are preserved byte-for-byte from the historical procedure and kept in their original order. Review names, addresses, paths and parameters before use.

Technical block 1
Get-KdsRootKey
Technical block 2
Add-KdsRootKey
Technical block 3
New-ADGroup -Name "GG-gMSA-App-HOSTS" -GroupScope Global -GroupCategory Security -Path "OU=Groupes,DC=contoso,DC=local"
Technical block 4
Add-ADGroupMember -Identity "GG-gMSA-App-HOSTS" -Members "SRV-APP01$","SRV-APP02$"
Technical block 5
New-ADServiceAccount -Name "gmsa-App" -DNSHostName "gmsa-app.contoso.local" -PrincipalsAllowedToRetrieveManagedPassword "GG-gMSA-App-HOSTS"
Technical block 6
Get-ADServiceAccount -Identity "gmsa-App" -Properties PrincipalsAllowedToRetrieveManagedPassword,ServicePrincipalNames | Format-List
Technical block 7
Install-ADServiceAccount -Identity "gmsa-App"
Technical block 8
Test-ADServiceAccount -Identity "gmsa-App"
Technical block 9
Get-Service -Name "NomDuService"
Technical block 10
Get-WinEvent -FilterHashtable @{LogName="System";StartTime=(Get-Date).AddMinutes(-15)} | Select-Object TimeCreated,Id,ProviderName,Message
Technical block 11
Test-ADServiceAccount -Identity "gmsa-App"
Technical block 12
Get-KdsRootKey

Validation

The procedure is validated when:

  • The original symptom or change request has been tested end to end.
  • The effective configuration matches the intended design and no unexplained error remains in the relevant logs.
  • Temporary troubleshooting controls have been removed and monitoring remains normal.
  • The result, evidence and any follow-up action are documented.

Rollback

  • Restore the configuration, policy, binding, route, credential assignment or service state recorded in the baseline when the change does not meet its success criteria.
  • Remove temporary rules, test objects and diagnostic settings that were introduced only for the procedure.
  • After rollback, repeat the minimum health checks to confirm that the previous service level has been restored.

Troubleshooting / common errors

  • Identity failures often combine DNS, time, replication, permissions and cached credentials; test each layer separately.
  • When policy is involved, verify the effective user/computer context rather than only the configured object.
  • If the result changes between tests, compare source, destination, identity, time and policy context before changing additional settings.
  • If a command succeeds but the application still fails, continue at the next protocol or application layer instead of widening access.
  • If the expected evidence is missing, verify that logging, auditing and the test path actually cover the failing component.
  • If the change does not improve the measured symptom, restore the previous state and reassess the working hypothesis.

Official and vendor references preserved from the original procedure

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