SV-253462r1268251: The LanMan authentication level must be set to send NTLMv2 response only, and to refuse LM and NTLM. | Microsoft Windows 11 STIG SCAP Benchmark

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Assessment Title

Rule Text

The LanMan authentication level must be set to send NTLMv2 response only, and to refuse LM and NTLM.

Description

Discussion Text

The Kerberos v5 authentication protocol is the default for authentication of users who are logging on to domain accounts. NTLM, which is less secure, is retained in later Windows versions for compatibility with clients and servers that are running earlier versions of Windows or applications that still use it. It is also used to authenticate logons to stand-alone computers that are running later versions.

How this relates to the STIG checklist: STIG vs SCAP benchmark.

IA Controls

NIST SP 800-53

Not mappedCCI-000366

References

DPMS Target Microsoft Windows 11 DISA DPMS Target Microsoft Windows 11 5471

SCC Automation Reference

The reconstructed evaluation script behind this rule's OVAL check(s) — every module a compound check combines, with this rule's own concrete values and DISA's SCC tool's real per-module mechanism curated from static teardown of SCC releases.

# Windows PowerShell
# Reconstructed from oval:mil.disa.stig.windows11:def:253462
# The LanMan authentication level must be set to send NTLMv2 response only, and to refuse LM and NTLM.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Verifies 'Network security: LAN Manager authentication level' is set to 'Send NTLMv2 response only. Refuse LM & NTLM' (Level 5)
# registry_object (registry_test)
function test_1 {
  return (((@{String='reg_sz';ExpandString='reg_expand_sz';Binary='reg_binary';DWord='reg_dword';MultiString='reg_multi_sz';QWord='reg_qword';None='reg_none'}[(Get-Item -Path 'Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa').GetValueKind('LmCompatibilityLevel').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Lsa' -Name 'LmCompatibilityLevel' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'LmCompatibilityLevel') -eq 5))
}

if (test_1) {
  Write-Output "PASS"
} else {
  Write-Output "FAIL"
}

Assessment Script Powered by AISyntax-verified

A standalone PowerShell script to assess this control automatically. Review before running it in your environment.

Syntax-checked as valid PowerShell. Not executed here — running it for real needs the actual ms_windows_11 target this check assesses.

# OVAL Definition: oval:mil.disa.stig.windows11:def:253462
$regPath = "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa"
$regKey = "LmCompatibilityLevel"
$regValue = 5
if (Test-Path $regPath) {
    $regData = Get-ItemProperty -Path $regPath -Name $regKey -ErrorAction SilentlyContinue
    if ($regData -and $regData.$regKey -eq $regValue) {
        Write-Output "PASS"; exit 0
    }
}
Write-Output "FAIL"; exit 1

Remediation

Configure the policy value for Computer Configuration >> Windows Settings >> Security Settings >> Local Policies >> Security Options >> "Network security: LAN Manager authentication level" to "Send NTLMv2 response only. Refuse LM & NTLM".