How to Disable Auto Login in Windows Using a PowerShell Script for Enhanced Security

As cyber threats continue to evolve, IT professionals must constantly stay vigilant to ensure robust security protocols. One such measure is the disabling of automatic login on Windows systems. This article will delve into the importance of this practice and provide a comprehensive guide on how to achieve this using a PowerShell script. This script not only disables automatic login but also ensures a login banner is presented, enhancing overall security.

Background

Automatic login, while convenient for users, poses significant security risks, especially in environments where sensitive data is accessible. Disabling this feature forces users to authenticate each time they log in, providing an additional layer of security. For IT professionals and Managed Service Providers (MSPs), automating this process via scripts can save time and ensure consistency across multiple systems.

The Script:

#Requires -Version 5.1

<#
.SYNOPSIS
    Disables the automatic login feature and ensures that a dialog box is presented each time a user signs in.
.DESCRIPTION
    Disables the automatic login feature and ensures that a dialog box is presented each time a user signs in.
.EXAMPLE
    -Title "A Title" -Message "A Message"
    
    Retrieving existing security policy...
                                                                           
    The task has completed successfully.
    See log %windir%\security\logs\scesrv.log for detail info.
    Modifying policy to include the login banner.
    Applying updated policy...
    Completed 5 percent (0/18) 	Process Security Policy area        
    Completed 22 percent (3/18) 	Process Security Policy area        
    Completed 44 percent (7/18) 	Process Security Policy area        
    Completed 61 percent (10/18) 	Process Security Policy area        
    Completed 77 percent (13/18) 	Process Security Policy area        
    Completed 100 percent (18/18) 	Process Security Policy area        
                                                                            
    The task has completed successfully.
    See log %windir%\security\logs\scesrv.log for detail info.


PARAMETER: -Title "ReplaceMeWithYourDesiredTitle"
    Specify the title of the dialog box to be used in the logon banner.

PARAMETER: -Message "ReplaceMeWithYourDesiredMessage"
    Specify the main text body to be used in the logon banner. 

PARAMETER: -MicrosoftDefaults
    Reverts all the modified settings to their Microsoft default value.

PARAMETER: -ForceRestart
    Schedules a restart for 60 seconds from now so that the login banner may take immediate effect.

.NOTES
    Minimum OS Architecture Supported: Windows 10, Windows Server 2016
    Release Notes: Initial Release
By using this script, you indicate your acceptance of the following legal terms as well as our Terms of Use at https://www.ninjaone.com/terms-of-use.
    Ownership Rights: NinjaOne owns and will continue to own all right, title, and interest in and to the script (including the copyright). NinjaOne is giving you a limited license to use the script in accordance with these legal terms. 
    Use Limitation: You may only use the script for your legitimate personal or internal business purposes, and you may not share the script with another party. 
    Republication Prohibition: Under no circumstances are you permitted to re-publish the script in any script library or website belonging to or under the control of any other software provider. 
    Warranty Disclaimer: The script is provided “as is” and “as available”, without warranty of any kind. NinjaOne makes no promise or guarantee that the script will be free from defects or that it will meet your specific needs or expectations. 
    Assumption of Risk: Your use of the script is at your own risk. You acknowledge that there are certain inherent risks in using the script, and you understand and assume each of those risks. 
    Waiver and Release: You will not hold NinjaOne responsible for any adverse or unintended consequences resulting from your use of the script, and you waive any legal or equitable rights or remedies you may have against NinjaOne relating to your use of the script. 
    EULA: If you are a NinjaOne customer, your use of the script is subject to the End User License Agreement applicable to you (EULA).
#>

[CmdletBinding()]
param (
    [Parameter()]
    [String]$Title,
    [Parameter()]
    [String]$Message,
    [Parameter()]
    [Switch]$MicrosoftDefaults = [System.Convert]::ToBoolean($env:revertToMicrosoftDefaults),
    [Parameter()]
    [Switch]$ForceRestart = [System.Convert]::ToBoolean($env:forceRestart)
)

begin {
    if ($env:logonBannerTitle -and $env:logonBannerTitle -notlike "null") { $Title = $env:logonBannerTitle }
    if ($env:logonBannerText -and $env:logonBannerText -notlike "null") { $Message = $env:logonBannerText }

    # Check if a title is provided. If it exists, trim any leading or trailing whitespace.
    if ($Title) {
        $Title = $Title.Trim()
    }

    # If no title is provided and Microsoft defaults are not being used, output an error and exit the script.
    if (!$Title -and !$MicrosoftDefaults) {
        Write-Host "[Error] Missing title for the login banner."
        exit 1
    }

    # Check if a message is provided. If it exists, trim any leading or trailing whitespace.
    if ($Message) {
        $Message = $Message.Trim()
    }

    # If no message is provided and Microsoft defaults are not being used, output an error and exit the script.
    if (!$Message -and !$MicrosoftDefaults) {
        Write-Host "[Error] Missing message for the login banner."
        exit 1
    }

    # If Microsoft defaults are specified to be used but either a title or message is also provided, error out due to the title and message not being present by default.
    if ($MicrosoftDefaults -and ($Title -or $Message)) {
        Write-Host "[Error] A login banner is not present by default. If you use the 'Revert To Microsoft Defaults' checkmark, leave the 'Login Banner Title' and the 'Login Banner Text' empty."
        exit 1
    }

    function Test-IsDomainJoined {
        if ($PSVersionTable.PSVersion.Major -lt 5) {
            return $(Get-WmiObject -Class Win32_ComputerSystem).PartOfDomain
        }
        else {
            return $(Get-CimInstance -Class Win32_ComputerSystem).PartOfDomain
        }
    }

    function Set-RegKey {
        param (
            $Path,
            $Name,
            $Value,
            [ValidateSet("DWord", "QWord", "String", "ExpandedString", "Binary", "MultiString", "Unknown")]
            $PropertyType = "DWord"
        )

        # Check if the specified path exists, if not, create it.
        if (-not $(Test-Path -Path $Path)) {
            New-Item -Path $Path -Force | Out-Null
        }

        # Check if the property already exists at the path.
        if ((Get-ItemProperty -Path $Path -Name $Name -ErrorAction SilentlyContinue)) {

            # Retrieve the current value of the registry key.
            $CurrentValue = (Get-ItemProperty -Path $Path -Name $Name -ErrorAction SilentlyContinue).$Name
            try {
                # Attempt to update the property's value.
                Set-ItemProperty -Path $Path -Name $Name -Value $Value -Force -Confirm:$false -ErrorAction Stop | Out-Null
            }
            catch {
                # If an error occurs during the update, print an error message and exit.
                Write-Host "[Error] Unable to Set registry key for $Name please see below error!"
                Write-Host "[Error] $($_.Message)"
                exit 1
            }
            # Print a confirmation of the change.
            Write-Host "$Path\$Name changed from $CurrentValue to $($(Get-ItemProperty -Path $Path -Name $Name -ErrorAction SilentlyContinue).$Name)"
        }
        else {
            try {
                # If the property does not exist, create it with the specified value and type.
                New-ItemProperty -Path $Path -Name $Name -Value $Value -PropertyType $PropertyType -Force -Confirm:$false -ErrorAction Stop | Out-Null
            }
            catch {
                # If an error occurs during creation, print an error message and exit.
                Write-Host "[Error] Unable to Set registry key for $Name please see below error!"
                Write-Host "[Error] $($_.Exception.Message)"
                exit 1
            }

            # Print a confirmation of the change.
            Write-Host "Set $Path\$Name to $($(Get-ItemProperty -Path $Path -Name $Name -ErrorAction SilentlyContinue).$Name)"
        }
    }
    function Test-IsElevated {
        $id = [System.Security.Principal.WindowsIdentity]::GetCurrent()
        $p = New-Object System.Security.Principal.WindowsPrincipal($id)
        $p.IsInRole([System.Security.Principal.WindowsBuiltInRole]::Administrator)
    }

    if (!$ExitCode) {
        $ExitCode = 0
    }
}
process {
    # Check if the current user session is elevated with administrator privileges. If not, display an error message and exit the script.
    if (!(Test-IsElevated)) {
        Write-Host -Object "[Error] Access Denied. Please run with Administrator privileges."
        exit 1
    }

    # Retrieve the AutoAdminLogon and DefaultPassword registry values to check for automatic login settings and stored passwords.
    $AutoLogin = Get-ItemProperty -Path "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" -Name "AutoAdminLogon" -ErrorAction SilentlyContinue | Select-Object -ExpandProperty "AutoAdminLogon" -ErrorAction SilentlyContinue
    $DefaultPassword = Get-ItemProperty -Path "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" -Name "DefaultPassword" -ErrorAction SilentlyContinue | Select-Object -ExpandProperty "DefaultPassword" -ErrorAction SilentlyContinue
    $PasswordLessSetting = Get-ItemProperty -Path "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\PasswordLess\Device" -Name "DevicePasswordLessBuildVersion" -ErrorAction SilentlyContinue | Select-Object -ExpandProperty "DevicePasswordLessBuildVersion" -ErrorAction SilentlyContinue

    # Alert if a password is stored in the registry, which might be insecure if in plain text.
    if ($DefaultPassword) {
        Write-Host "[Alert] A Password is stored in HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon\DefaultPassword. This password is likely in plain text."
    }

    # Check if the device is part of a domain, and if so, recommend using group policy for login banner settings.
    if (Test-IsDomainJoined) {
        Write-Host "[Error] This device is domain joined. Login Banner modifications should be setup using group policy."
        Write-Host "[Info] Group Policy Location: Computer Configuration > Windows Settings > Security Settings > Local Policies > Security Options > Interactive logon:(...)"
        Write-Host "[Info] https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-10/security/threat-protection/security-policy-settings/interactive-logon-message-text-for-users-attempting-to-log-on"
        exit 1
    }

    # Turn off automatic login if it is enabled.
    if ($AutoLogin -ne 0) {
        Set-RegKey -Path "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\Winlogon" -Name "AutoAdminLogon" -Value 0
    }

    # Disable automatic login if it is enabled
    if ($PasswordLessSetting -eq 0) {
        Set-RegKey -Path "Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows NT\CurrentVersion\PasswordLess\Device" -Name "DevicePasswordLessBuildVersion" -Value 2
    }

    # Announce the start of the security policy retrieval process.
    Write-Host "Retrieving existing security policy..."

    # Export the current security policy and record the output to a temporary file.
    $SecurityPolicyPath = "$env:TEMP\enable-loginbanner.cfg"
    $ExportPolicy = Start-Process SecEdit.exe -ArgumentList "/export /cfg $SecurityPolicyPath" -RedirectStandardOutput "$env:TEMP\enable-loginbanner.txt" -NoNewWindow -Wait -PassThru
    $ExportPolicyOutput = Get-Content -Path "$env:TEMP\enable-loginbanner.txt"

    # Display the output of the policy export and clean up the temporary file.
    if ($ExportPolicyOutput) {
        $ExportPolicyOutput | Write-Host
        Remove-Item "$env:TEMP\enable-loginbanner.txt"
    }

    # Check the exit code of the export process and display an error message if the export failed.
    if ($ExportPolicy.ExitCode -ne 0) {
        Write-Host -Object "Exit Code: $($ExportPolicy.ExitCode)"
        Write-Host -Object "[Error] Unable to edit security policy."
        exit 1
    }
    
    # Check if Microsoft default settings are specified to modify the login banner.
    if ($MicrosoftDefaults) {
        Write-Host "Removing login banner from security policy..."

        # Initialize a new list to store modified security policy settings.
        $NewSecPolicy = New-Object System.Collections.Generic.List[string]

        # Read the current security policy and process each line.
        Get-Content $SecurityPolicyPath | ForEach-Object {

            # If the line contains settings for LegalNoticeCaption or LegalNoticeText, reset these values.
            if ($_ -match "LegalNoticeCaption" -or $_ -match "LegalNoticeText") {
                $NewSecPolicy.Add(($_ -replace ",.*", ","))
            }
            else {
                $NewSecPolicy.Add($_)
            }
        }

        # Write the modified security policy back to the configuration file.
        $NewSecPolicy | Out-File $SecurityPolicyPath

        Write-Host "Applying updated policy..."
        # Apply the modified security policy using SecEdit.exe.
        $UpdateSecurityPolicy = Start-Process SecEdit.exe -ArgumentList "/configure /db c:\windows\security\local.sdb /cfg $SecurityPolicyPath" -RedirectStandardOutput "$env:TEMP\enable-loginbanner.txt" -Wait -NoNewWindow -PassThru
    
        # Capture the output from the policy update and display it.
        $UpdatePolicyOutput = Get-Content -Path "$env:TEMP\enable-loginbanner.txt"
        if ($UpdatePolicyOutput) {
            $UpdatePolicyOutput | Write-Host
            Remove-Item "$env:TEMP\enable-loginbanner.txt"
        }
    

        # Check the exit code of the policy update process and handle errors.
        if ($UpdateSecurityPolicy.ExitCode -ne 0) {
            Write-Host -Object "Exit Code: $($UpdateSecurityPolicy.ExitCode)"
            Write-Host -Object "[Error] Unable to update security policy."
            exit 1
        }
        else {

            if ($ForceRestart) {
                Write-Warning -Message "Scheduling system restart for 60 seconds from now. $((Get-Date).AddMinutes(60))"
                Start-Process shutdown.exe -ArgumentList "/r /t 60" -Wait -NoNewWindow
            }
            else {
                Write-Warning -Message "A restart may be required for the login banner to be removed. Please restart at your earliest convenience."
            }
            
            exit $ExitCode
        }
    }

    # Begin modification to include the login banner in the security policy.
    Write-Host "Modifying policy to include the login banner."

    # Check if the current policy already includes a title for the login banner.
    if (Get-Content $SecurityPolicyPath | Where-Object { $_ -like "*LegalNoticeCaption*" }) {
        # Replace the existing title with a new one, maintaining other parts of the line.
        $Caption = (Get-Content $SecurityPolicyPath | Where-Object { $_ -like "*LegalNoticeCaption*" }) -replace ',.*', ",`"$Title`""
        (Get-Content $SecurityPolicyPath) -replace ".*LegalNoticeCaption.*", "$Caption" | Out-File $SecurityPolicyPath
    }
    else {
        # If no title is present, create a new list for the modified policy settings.
        $NewSecPolicy = New-Object System.Collections.Generic.List[string]
        # Define the new title setting with the specified title
        $Caption = "MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\LegalNoticeCaption=1,`"$Title`""

        # Read the current policy and add the new title setting where appropriate.
        Get-Content $SecurityPolicyPath | ForEach-Object {
            if ($_ -match "\[Registry Values\]") {
                $NewSecPolicy.Add($_)
                $NewSecPolicy.Add($Caption)
            }
            else {
                $NewSecPolicy.Add($_)
            }
        }

        # Write the modified settings back to the configuration file.
        $NewSecPolicy | Out-File $SecurityPolicyPath
    }

    # Check if the security policy file shows that the login banner text has already been set.
    if (Get-Content $SecurityPolicyPath | Where-Object { $_ -like "*LegalNoticeText*" }) {
        # If the setting is found, modify its existing entry by replacing the existing text after the comma
        # with a formatted version of $Message. Commas in $Message are replaced with '","', and new lines are replaced with commas.
        $Text = (Get-Content $SecurityPolicyPath | Where-Object { $_ -like "*LegalNoticeText*" }) -replace ',.*', ",$($Message -replace ',','","' -replace '\n',',')"
        
        # Replace the entire line that contains "LegalNoticeText" with the new formatted text, and overwrite the file.
        (Get-Content $SecurityPolicyPath) -replace ".*LegalNoticeText.*", "$Text" | Out-File $SecurityPolicyPath
    }
    else {
        # If the setting is not found in the file, initialize a new list to store all lines for the updated policy.
        $NewSecPolicy = New-Object System.Collections.Generic.List[string]

        # Create a new line for "LegalNoticeText" with the provided $Message formatted similarly to the replacement process above.
        $Text = "MACHINE\Software\Microsoft\Windows\CurrentVersion\Policies\System\LegalNoticeText=7,$($Message -replace ',','","' -replace '\n',',')"

        # Read each line of the security policy. If the line matches "[Registry Values]", it indicates the start of registry settings.
        Get-Content $SecurityPolicyPath | ForEach-Object {
            if ($_ -match "\[Registry Values\]") {
                # Add the current line and immediately follow it with the new "LegalNoticeText" setting.
                $NewSecPolicy.Add($_)
                $NewSecPolicy.Add($Text)
            }
            else {
                # Add other lines without modification.
                $NewSecPolicy.Add($_)
            }
        }

        # Write the updated list back to the security policy file, thus including the new "LegalNoticeText".
        $NewSecPolicy | Out-File $SecurityPolicyPath
    }

    # Display a message indicating that the updated security policy is being applied.
    Write-Host "Applying updated policy..."
    $UpdateSecurityPolicy = Start-Process SecEdit.exe -ArgumentList "/configure /db c:\windows\security\local.sdb /cfg $SecurityPolicyPath /areas securitypolicy" -RedirectStandardOutput "$env:TEMP\enable-loginbanner.txt" -Wait -NoNewWindow -PassThru
    
    $UpdatePolicyOutput = Get-Content -Path "$env:TEMP\enable-loginbanner.txt"
    # If there is any output from the SecEdit process, display it in the console.
    if ($UpdatePolicyOutput) {
        $UpdatePolicyOutput | Write-Host
        Remove-Item "$env:TEMP\enable-loginbanner.txt"
    }
    

    # Check if the SecEdit process completed successfully by examining the exit code.
    if ($UpdateSecurityPolicy.ExitCode -ne 0) {
        Write-Host -Object "Exit Code: $($UpdateSecurityPolicy.ExitCode)"
        Write-Host -Object "[Error] Unable to update security policy."
        exit 1
    }

    if ($ForceRestart) {
        Write-Warning -Message "Scheduling system restart for 60 seconds from now. $((Get-Date).AddMinutes(60))"
        Start-Process shutdown.exe -ArgumentList "/r /t 60" -Wait -NoNewWindow
    }
    else {
        Write-Warning -Message "A restart may be required for the login banner to take effect. Please restart at your earliest convenience."
    }
    
    exit $ExitCode
}
end {
    
    
    
}

 

Detailed Breakdown

This PowerShell script is designed to disable automatic login and ensure that a dialog box is presented each time a user signs in. Here’s a step-by-step explanation of how it works:

1. Parameters and Initial Checks: The script accepts parameters for the title and message of the login banner, and switches for reverting to Microsoft defaults and forcing a restart. It begins by checking if these parameters are provided, trimming any leading or trailing whitespace. If essential parameters are missing and Microsoft defaults are not being used, the script exits with an error message.
2. Domain Check: A function Test-IsDomainJoined checks if the device is part of a domain. If it is, the script advises using group policy for login banner settings and exits. This ensures compliance with domain policies and prevents conflicts.
3. Registry Key Modification: The Set-RegKey function is used to create or modify registry keys that control automatic login settings. If automatic login is enabled (AutoAdminLogon registry value is not 0), it is set to 0. Similarly, if the passwordless login setting is enabled, it is disabled by setting the DevicePasswordLessBuildVersion value to 2.
4. Security Policy Export and Modification: The script exports the current security policy using SecEdit.exe and processes the configuration file to include or modify settings for the login banner. If Microsoft defaults are requested, it removes any existing login banner settings. Otherwise, it updates the LegalNoticeCaption and LegalNoticeText with the provided title and message.
5. Applying the Updated Policy: After modifying the configuration file, the script applies the updated security policy using SecEdit.exe. If a restart is forced, it schedules a system restart to ensure the changes take effect immediately.
6. Final Steps: The script provides feedback throughout its execution, indicating the status of each operation and any errors encountered.

Potential Use Cases

Imagine an IT professional managing a fleet of laptops for a financial institution. Ensuring that each device requires a login upon startup is crucial for protecting sensitive financial data. By using this script, the IT professional can automate the process across all devices, ensuring compliance with security policies and saving time on manual configuration.

Comparisons

While group policies are the preferred method for domain-joined devices, this script offers a straightforward solution for standalone systems or small workgroups. Compared to manual registry editing or using third-party tools, this script is more efficient and reduces the risk of human error.

FAQs

• Can this script be used on all versions of Windows? This script is designed for Windows 10 and Windows Server 2016 and later versions.
• What happens if I provide both Microsoft defaults and custom title/message? The script will throw an error, as it is not intended to mix these settings.
• Is a restart necessary? A restart is recommended to ensure the login banner settings take effect.
• Can this script be run without administrator privileges? No, the script must be run with administrator privileges to modify registry settings and apply security policies.

Implications

Disabling automatic login and implementing a login banner enhances security by ensuring users authenticate themselves and acknowledge any security notices. This practice reduces the risk of unauthorized access and ensures compliance with security protocols.

Recommendations

• Always test the script on a single machine before deploying it widely.

• Use descriptive titles and messages for the login banner to provide clear instructions or warnings to users.

• Schedule regular reviews of security policies to adapt to evolving security threats.

Final Thoughts

For IT professionals and MSPs, ensuring robust security measures is paramount. Disabling automatic login and implementing login banners are critical steps in protecting sensitive data. This PowerShell script provides an efficient and automated way to achieve these goals. Additionally, using tools like NinjaOne can further enhance security management by providing centralized control and monitoring capabilities.