Block NTLM (LM, NTLM, NTLMv2)

ComputerIntune-readyPol_BlockNTLM

Supported on At least Windows Server 2025, Windows 11

25H2 · 1.0

What it does

This policy controls if the SMB client will block NTLM for remote connection authentication. If you enable this policy setting, the SMB client won't use NTLM for remote connection authentication. If you disable or do not configure this policy setting, the SMB client can still use NTLM.

What it writes

Hive: HKEY_LOCAL_MACHINE
Registry key: Software\Policies\Microsoft\Windows\LanmanWorkstation
Value name: BlockNTLM
When enabled: DWORD 1
When disabled: DWORD 0

In Intune

No native CSP; import the ADMX (Intune-ready).

From Microsoft's Policy CSP DDF files (DDF v2 Files, February 2026), read 18 Oct 2026.

Configure and deploy

Choose a state; the output below is generated from the template for exactly that.

Enabled · Computer · template defaults

Registry file (.reg)

Windows Registry Editor Version 5.00

[HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\LanmanWorkstation]
"BlockNTLM"=dword:00000001

PowerShell

$ErrorActionPreference = 'Stop'

function Set-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $PropertyType,
        [Parameter(Mandatory = $true)][object] $Value
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        New-Item -Path $Path -Force | Out-Null
    }

    New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}

function Remove-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (Test-Path -LiteralPath $Path) {
        Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
    }
}

function Clear-RegistryKeyValues {
    param(
        [Parameter(Mandatory = $true)][string] $Path
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return
    }

    foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
        Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
    }
}

# Policy: Block NTLM (LM, NTLM, NTLMv2)
# Name: Pol_BlockNTLM
# Scope: Machine
# State: Enabled
# Source: LanmanWorkstation.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\LanmanWorkstation' -Name 'BlockNTLM' -PropertyType 'DWord' -Value 1

The OMA-URI is an inferred ADMX-backed Policy CSP candidate derived from the source ADMX file name and policy name.
Some Microsoft policies use built-in Policy CSP pages whose area names don't match the ADMX file name, so verify the candidate against Microsoft Learn before deployment.

ADMX profile candidate (OMA-URI)

./Device/Vendor/MSFT/Policy/Config/ADMX_LanmanWorkstation/Pol_BlockNTLM

ADMX SyncML candidate

<SyncML xmlns="SYNCML:SYNCML1.2">
  <SyncBody>
    <Replace>
      <CmdID>1</CmdID>
      <Item>
        <Meta>
          <Format>chr</Format>
          <Type>text/plain</Type>
        </Meta>
        <Target>
          <LocURI>./Device/Vendor/MSFT/Policy/Config/ADMX_LanmanWorkstation/Pol_BlockNTLM</LocURI>
        </Target>
        <Data>&lt;enabled/&gt;</Data>
      </Item>
    </Replace>
    <Final/>
  </SyncBody>
</SyncML>

Intune remediation scripts

Detection

$ErrorActionPreference = 'Stop'
$reasons = [System.Collections.Generic.List[string]]::new()

function Test-RegistryValueExists {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return $false
    }

    return $null -ne (Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue)
}

function Test-RegistryValueEquals {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $Kind,
        [Parameter(Mandatory = $true)][object] $Expected
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return $false
    }

    $valueObject = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction SilentlyContinue
    if ($null -eq $valueObject) {
        return $false
    }

    $actual = $valueObject.$Name
    switch ($Kind) {
        'String' { return [string]$actual -ceq [string]$Expected }
        'ExpandString' { return [string]$actual -ceq [string]$Expected }
        'DWord' { return [uint32]$actual -eq [uint32]$Expected }
        'QWord' { return [uint64]$actual -eq [uint64]$Expected }
        'MultiString' {
            $actualArray = @($actual)
            $expectedArray = @($Expected)
            if ($actualArray.Count -ne $expectedArray.Count) { return $false }
            for ($index = 0; $index -lt $actualArray.Count; $index++) {
                if ([string]$actualArray[$index] -cne [string]$expectedArray[$index]) { return $false }
            }
            return $true
        }
        'Binary' {
            $actualArray = [byte[]]$actual
            $expectedArray = [byte[]]$Expected
            if ($actualArray.Length -ne $expectedArray.Length) { return $false }
            for ($index = 0; $index -lt $actualArray.Length; $index++) {
                if ($actualArray[$index] -ne $expectedArray[$index]) { return $false }
            }
            return $true
        }
        default { return [string]$actual -ceq [string]$Expected }
    }
}

# Policy: Block NTLM (LM, NTLM, NTLMv2)
# Name: Pol_BlockNTLM
# Scope: Machine
# State: Enabled
# Source: LanmanWorkstation.admx

$isMatch = Test-RegistryValueEquals -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\LanmanWorkstation' -Name 'BlockNTLM' -Kind 'DWord' -Expected 1
if (-not $isMatch) {
    $reasons.Add('Value mismatch: HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\LanmanWorkstation\BlockNTLM') | Out-Null
}

if ($reasons.Count -eq 0) {
    Write-Output 'Compliant'
    exit 0
}

$reasons | ForEach-Object { Write-Output $_ }
exit 1

Remediation

$ErrorActionPreference = 'Stop'

function Set-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name,
        [Parameter(Mandatory = $true)][string] $PropertyType,
        [Parameter(Mandatory = $true)][object] $Value
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        New-Item -Path $Path -Force | Out-Null
    }

    New-ItemProperty -LiteralPath $Path -Name $Name -PropertyType $PropertyType -Value $Value -Force | Out-Null
}

function Remove-RegistryValue {
    param(
        [Parameter(Mandatory = $true)][string] $Path,
        [Parameter(Mandatory = $true)][string] $Name
    )

    if (Test-Path -LiteralPath $Path) {
        Remove-ItemProperty -LiteralPath $Path -Name $Name -Force -ErrorAction SilentlyContinue
    }
}

function Clear-RegistryKeyValues {
    param(
        [Parameter(Mandatory = $true)][string] $Path
    )

    if (-not (Test-Path -LiteralPath $Path)) {
        return
    }

    foreach ($propertyName in (Get-Item -LiteralPath $Path).Property) {
        Remove-ItemProperty -LiteralPath $Path -Name $propertyName -Force -ErrorAction SilentlyContinue
    }
}

# Policy: Block NTLM (LM, NTLM, NTLMv2)
# Name: Pol_BlockNTLM
# Scope: Machine
# State: Enabled
# Source: LanmanWorkstation.admx

Set-RegistryValue -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\LanmanWorkstation' -Name 'BlockNTLM' -PropertyType 'DWord' -Value 1

History 5 retained releases

24H2 · 1.030 Sep 2024
- Added in this release.

1 later release left it unchanged.

Template

Internal name: Pol_BlockNTLM
Namespace: Microsoft.Policies.LanmanWorkstation
Template file: LanmanWorkstation.admx
Release: Windows 11 25H2 · 1.0 · file set de4e49983ebd651f…

Definition, editor controls and support

Definition

<policy class="Machine" displayName="$(string.Pol_BlockNTLM_Name)" explainText="$(string.Pol_BlockNTLM_Help)" key="Software\Policies\Microsoft\Windows\LanmanWorkstation" name="Pol_BlockNTLM" valueName="BlockNTLM" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.LanmanWorkstation:Cat_LanmanWorkstation" />
      <supportedOn ref="Microsoft.Policies.LanmanWorkstation:SUPPORTED_Windows_Server_2025_Windows_11_0" />
      <enabledValue>
        <decimal value="1" />
      </enabledValue>
      <disabledValue>
        <decimal value="0" />
      </disabledValue>
    </policy>

Editor controls

Supported platforms and category

Microsoft.Policies.LanmanWorkstation:category:Cat_LanmanWorkstation
<category displayName="$(string.Cat_LanmanWorkstation)" name="Cat_LanmanWorkstation" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Windows:Network" />
    </category>
Microsoft.Policies.LanmanWorkstation:definition:SUPPORTED_Windows_Server_2025_Windows_11_0
<definition displayName="$(string.SUPPORTED_Windows_Server_2025_Windows_11_0)" name="SUPPORTED_Windows_Server_2025_Windows_11_0" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      </definition>
Microsoft.Policies.Windows:category:Network
<category displayName="$(string.Network)" explainText="$(string.Network_Help)" name="Network" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
Microsoft.Policies.LanmanWorkstation:category:Cat_LanmanWorkstation
<category displayName="$(string.Cat_LanmanWorkstation)" name="Cat_LanmanWorkstation" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      <parentCategory ref="Microsoft.Policies.Windows:Network" />
    </category>
<strings><string id="Microsoft.Policies.LanmanWorkstation:Cat_LanmanWorkstation">Lanman Workstation</string></strings>
Microsoft.Policies.LanmanWorkstation:definition:SUPPORTED_Windows_Server_2025_Windows_11_0
<definition displayName="$(string.SUPPORTED_Windows_Server_2025_Windows_11_0)" name="SUPPORTED_Windows_Server_2025_Windows_11_0" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions">
      </definition>
<strings><string id="Microsoft.Policies.LanmanWorkstation:SUPPORTED_Windows_Server_2025_Windows_11_0">At least Windows Server 2025, Windows 11</string></strings>
Microsoft.Policies.Windows:category:Network
<category displayName="$(string.Network)" explainText="$(string.Network_Help)" name="Network" xmlns="http://schemas.microsoft.com/GroupPolicy/2006/07/PolicyDefinitions" />
<strings><string id="Microsoft.Policies.Windows:Network">Network</string><string id="Microsoft.Policies.Windows:Network_Help">Allows configuration of components of the operating system used by a client computer to connect to a network. This includes DNS settings and Offline Files.</string></strings>