SV-225009r958478: Local users on domain-joined computers must not be enumerated. | Microsoft Windows Server 2016 STIG SCAP Benchmark

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Assessment Title

Rule Text

Local users on domain-joined computers must not be enumerated.

Description

Discussion Text

The username is one part of logon credentials that could be used to gain access to a system. Preventing the enumeration of users limits this information to authorized personnel.

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

IA Controls

NIST SP 800-53

Not mappedCCI-000381V-73533SV-88187

References

DPMS Target Microsoft Windows Server 2016 DISA DPMS Target Microsoft Windows Server 2016 4205

Checks

DISA STIG (Manual Reference)

This applies to member servers. For domain controllers and standalone or nondomain-joined systems, this is NA.

If the following registry value does not exist or is not configured as specified, this is a finding.

Registry Hive: HKEY_LOCAL_MACHINE
Registry Path: \SOFTWARE\Policies\Microsoft\Windows\System\

Value Name: EnumerateLocalUsers

Type: REG_DWORD
Value: 0x00000000 (0)

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.windows:def:1173
# Local users on domain-joined computers must not be enumerated.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# If system is a Member Server
# wmi57_object (wmi57_test)
function test_1 {
  return (((Get-CimInstance -Namespace 'root\cimv2' -Query 'SELECT DomainRole FROM win32_computersystem' | Select-Object -First 1) | Select-Object -ExpandProperty 'DomainRole') -eq '3')
}
# Verifies 'Enumerate local users on domain-joined computers' is set to 'Disabled'
# registry_object (registry_test)
function test_2 {
  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\Software\Policies\Microsoft\Windows\System').GetValueKind('EnumerateLocalUsers').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows\System' -Name 'EnumerateLocalUsers' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'EnumerateLocalUsers') -eq 0))
}

if ((-not (test_1) -or test_2)) {
  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_server_2016 target this check assesses.

# OVAL Definition: oval:mil.disa.stig.windows:def:1173
$isMemberServer = (Get-CimInstance -ClassName Win32_ComputerSystem).DomainRole -eq 3
if ($isMemberServer) { exit 0 }
$registryPath = "HKLM:\Software\Policies\Microsoft\Windows\System"
if (-Not (Test-Path -Path $registryPath)) { exit 0 }
$enumValue = (Get-ItemProperty -Path $registryPath -Name EnumerateLocalUsers -ErrorAction SilentlyContinue).EnumerateLocalUsers
if ($enumValue -eq 0) { exit 0 }
exit 1

Remediation

Configure the policy value for Computer Configuration >> Administrative Templates >> System >> Logon >> "Enumerate local users on domain-joined computers" to "Disabled".