SV-29012r1: The Send download LanMan compatible password option is not set to Send NTLMv2 response only\refuse LM. | Windows Vista Security Technical Implementation Guide

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Assessment Title

Rule Text

The Send download LanMan compatible password option is not set to Send NTLMv2 response only\refuse LM.

Description

Discussion Text

The Kerberos v5 authentication protocol is the default for authentication of users who are logging on to domain accounts. NTLM is retained in later Windows versions for compatibility with clients and servers that are running earlier versions of Windows. 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-000366CCE-4922-1

Additional Details

Potential Impacts

Setting this to the required setting may prevent authentication with older Operating Systems and break some applications.

Responsibility

Information Assurance Officer

References

DPMS Target Windows Vista DISA DPMS Target Windows Vista 1029

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.fso.windows:def:435
# The Send download LanMan compatible password option is not set to Send NTLMv2 response only\refuse LM.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# registry_object (registry_test)
function test_1 {
  return (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa' -Name 'LMCompatibilityLevel' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'LMCompatibilityLevel') -ge 4)
}
# registry_object (registry_test)
function test_2 {
  return (-not ($null -ne (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa' -Name 'LMCompatibilityLevel')))
}
# registry_object (registry_test)
function test_3 {
  return ($null -ne (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa' -Name 'LMCompatibilityLevel'))
}
# registry_object (registry_test)
function test_4 {
  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')
}
# registry_object (registry_test)
function test_5 {
  return (-not ($null -ne (Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\System\CurrentControlSet\Control\Lsa' -Name 'LMCompatibilityLevel')))
}

if (((test_1 -or test_2) -and test_3 -and (test_4 -or test_5))) {
  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 windows_vista target this check assesses.

# oval:mil.disa.fso.windows:def:435
if (!(Test-Path -Path "HKLM:\System\CurrentControlSet\Control\Lsa\LMCompatibilityLevel")) {exit 1} else {if ((Get-ItemProperty -Path "HKLM:\System\CurrentControlSet\Control\Lsa\LMCompatibilityLevel").LMCompatibilityLevel -ge 4) {exit 0} else {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 at least “Send NTLMv2 response only\refuse LM”.