SV-278656r1192817: Microsoft Defender AV must configure local administrator merge behavior for lists. | Microsoft Defender Antivirus STIG SCAP Benchmark

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Assessment Title

Rule Text

Microsoft Defender AV must configure local administrator merge behavior for lists.

Description

Discussion Text

This policy setting configures how locally defined lists are combined or merged with globally defined lists. This setting applies to exclusion lists, specified remediation lists, and attack surface reduction.

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

IA Controls

NIST SP 800-53

Not mappedCCI-001170

References

DPMS Target Microsoft Defender Antivirus DISA DPMS Target Microsoft Defender Antivirus 3985

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.windowsdefav:def:278656
# Microsoft Defender AV must configure local administrator merge behavior for lists.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Verifies 'Local administrator merge behavior for lists' is 'Enabled'
# 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\SOFTWARE\Policies\Microsoft\Windows Defender').GetValueKind('DisableLocalAdminMerge').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\SOFTWARE\Policies\Microsoft\Windows Defender' -Name 'DisableLocalAdminMerge' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'DisableLocalAdminMerge') -eq 1))
}

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_defender_antivirus target this check assesses.

# OVAL Definition: oval:mil.disa.stig.windowsdefav:def:278656
$regPath = "HKLM:\SOFTWARE\Policies\Microsoft\Windows Defender"
$regKey = "DisableLocalAdminMerge"
$regValue = 1

if (Test-Path $regPath) {
    $regData = Get-ItemProperty -Path $regPath -ErrorAction SilentlyContinue
    if ($regData -and $regData.DisableLocalAdminMerge -eq $regValue) {
        Write-Output "PASS"
        exit 0
    }
}
Write-Output "FAIL"
exit 1

Remediation

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Configure local administrator merge behavior for lists to "Enabled".