When you configure a Windows service to run under a domain account, the system doesn't actually store the password itself. Instead, it uses a special authentication token called the LSA secret (Local Security Authority secret). This encrypted credential storage mechanism allows services to continue running even after the domain password changes.

The service continues to work because Windows maintains two separate authentication processes:

• The initial authentication when the service starts
• Ongoing authentication during operation

Here's a PowerShell example to view service account configurations:

Get-WmiObject Win32_Service | 
Where-Object { $_.StartName -like "*domain*" } | 
Select-Object Name, StartName, State

The service will fail to start if:

• The password was changed and the service was stopped
• The computer lost domain trust
• The account was disabled or locked

To programmatically handle password updates, you can use this C# example with the ServiceController class:

using System.ServiceProcess;

void UpdateServicePassword(string serviceName, string account, string password)
{
    using (var sc = new ServiceController(serviceName))
    {
        var svcConfig = new ManagementPath($"Win32_Service.Name='{serviceName}'");
        using (var svc = new ManagementObject(svcConfig))
        {
            svc.InvokeMethod("Change", new object[] { 
                null, null, null, null, null, 
                false, account, password 
            });
        }
    }
}

For more robust solutions consider:

• Group Managed Service Accounts (gMSA)
• Using SC command line tool: sc config [servicename] obj= [domain\user] password= [password]
• Scheduled tasks with stored credentials

For critical services, implement monitoring that checks service account status:

$services = Get-WmiObject Win32_Service | Where StartName -like "*domain*"
foreach ($svc in $services) {
    $test = Test-Path "WinNT://$($svc.StartName.Replace('\','/'))"
    if (-not $test) { Write-Warning "$($svc.Name) may have credential issues" }
}

When configuring a Windows service to run under a domain user account, the credentials are stored in a special protected area of the Local Security Authority (LSA) subsystem. This storage mechanism allows the service to continue running even after the domain account password changes.

// Example of setting up a service with domain credentials
sc.exe create "MyService" binPath= "C:\service.exe" obj= "DOMAIN\username" password= "p@ssw0rd"

The service continues to run because Windows caches the credentials using the LSA secret mechanism. However, there are important caveats:

• If the service stops and needs to restart, it will fail unless the password is updated
• Some service operations (like certain types of service recovery actions) may trigger authentication checks

# PowerShell command to update service credentials
Set-Service -Name "MyService" -Credential (Get-Credential)

For production environments, consider these approaches:

• Use Group Managed Service Accounts (gMSA) for automatic password management
• Implement credential rotation scripts as part of your password change procedures
• Monitor service account expiration dates and password change policies

Here's a sample PowerShell script to handle credential updates:

$serviceName = "MyService"
$newCred = Get-Credential -Message "Enter new domain credentials"
$service = Get-WmiObject -Class Win32_Service -Filter "Name='$serviceName'"
$service.Change($null, $null, $null, $null, $null, $null, $newCred.UserName, $newCred.GetNetworkCredential().Password, $null, $null, $null)

When encountering service start failures after password changes:

1. Check Event Viewer for authentication errors (Event ID 7034)
2. Verify the account has "Logon as a service" right
3. Test the account credentials locally using runas /user:domain\account cmd