Network security: LAN Manager authentication level
Verified with Windows Security Options 25H2 — updated on July 13, 2026
Security policy
This is a Security Options policy (Windows Settings > Security Settings), applied by the security engine — not an Administrative Template (ADMX). In GPMC/gpedit it is configured under Local Policies > Security Options.
Path in the GPO console
Computer Configuration\Windows Settings\Security Settings\Local Policies\Security Options\Network security Description
This setting selects which LM or NTLM responses the computer sends and which protocols it accepts. Current Windows clients normally use NTLMv2 responses, while domain or baseline policy may enforce a stricter level. Higher levels reduce exposure to obsolete hashes and downgrade attacks, but can break authentication with legacy systems.
Registry
HKLM
System\CurrentControlSet\Control\Lsa Value name: LmCompatibilityLevel
Export Builder
BETAConfigure the state, scope and options, then generate .reg, PowerShell, Intune and SCCM outputs — or add the setting to a multi-setting collection.
These exports write the registry — this is not a managed GPO. ⓘ
Security policy setting: a domain GPO (Security Settings) can overwrite this registry value at the next policy refresh. Prefer configuring it via GPMC > Security Options.
.reg file
Windows Registry Editor Version 5.00
; Exported from gporais.com
; Policy: Network security: LAN Manager authentication level
; State: Enabled
[HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa]
"LmCompatibilityLevel"=dword:00000001
"LmCompatibilityLevel"=dword:00000000More formats (PowerShell, Intune, SCCM)
PowerShell
# Exported from gporais.com
# Policy: Network security: LAN Manager authentication level
# State: Enabled
$path = 'HKLM:\System\CurrentControlSet\Control\Lsa'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'LmCompatibilityLevel' -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name 'LmCompatibilityLevel' -Value 0 -Type DWordIntune XML
No direct Policy CSP / OMA-URI mapping for this policy. Use the Intune Remediation tab, or ingest the ADMX in Intune.Intune Remediation
# === Detection script ===
# Exported from gporais.com
# Policy: Network security: LAN Manager authentication level
# State: Enabled
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\System\CurrentControlSet\Control\Lsa' -Name 'LmCompatibilityLevel' -Expected 1 -Kind DWord)
(Test-RegistryValue -Path 'HKLM:\System\CurrentControlSet\Control\Lsa' -Name 'LmCompatibilityLevel' -Expected 0 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Network security: LAN Manager authentication level
# State: Enabled
$path = 'HKLM:\System\CurrentControlSet\Control\Lsa'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'LmCompatibilityLevel' -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name 'LmCompatibilityLevel' -Value 0 -Type DWordSCCM scripts
# Exported from gporais.com
# Policy: Network security: LAN Manager authentication level
# State: Enabled
# SCCM Configuration Item guidance:
# Create a Configuration Item of type "Setting: Script".
# Discovery script: use the Detection script below.
# Remediation script: use the Remediation script below.
# Compliance rule: the Discovery script output equals 'Compliant'.
# === Detection script ===
# Exported from gporais.com
# Policy: Network security: LAN Manager authentication level
# State: Enabled
function Test-RegistryValue {
param(
[Parameter(Mandatory = $true)][string]$Path,
[Parameter(Mandatory = $true)][string]$Name,
[object]$Expected,
[ValidateSet('String', 'DWord', 'MultiString')][string]$Kind = 'String',
[switch]$Absent
)
try {
$item = Get-ItemProperty -LiteralPath $Path -Name $Name -ErrorAction Stop
} catch {
return $Absent.IsPresent
}
if ($Absent.IsPresent) { return $false }
$actual = $item.$Name
if ($Kind -eq 'DWord') { return ([int64]$actual) -eq ([int64]$Expected) }
if ($Kind -eq 'MultiString') {
$actualValues = @($actual)
$expectedValues = @($Expected)
if ($actualValues.Count -ne $expectedValues.Count) { return $false }
for ($i = 0; $i -lt $expectedValues.Count; $i++) {
if ([string]$actualValues[$i] -ne [string]$expectedValues[$i]) { return $false }
}
return $true
}
return [string]$actual -eq [string]$Expected
}
$checks = @(
(Test-RegistryValue -Path 'HKLM:\System\CurrentControlSet\Control\Lsa' -Name 'LmCompatibilityLevel' -Expected 1 -Kind DWord)
(Test-RegistryValue -Path 'HKLM:\System\CurrentControlSet\Control\Lsa' -Name 'LmCompatibilityLevel' -Expected 0 -Kind DWord)
)
if ($checks -notcontains $false) {
Write-Output 'Compliant'
exit 0
}
Write-Output 'Non-compliant'
exit 1
# === Remediation script ===
# Exported from gporais.com
# Policy: Network security: LAN Manager authentication level
# State: Enabled
$path = 'HKLM:\System\CurrentControlSet\Control\Lsa'
New-Item -Path $path -Force | Out-Null
Set-ItemProperty -Path $path -Name 'LmCompatibilityLevel' -Value 1 -Type DWord
Set-ItemProperty -Path $path -Name 'LmCompatibilityLevel' -Value 0 -Type DWord