SV-278676r1192828: Microsoft Defender AV must scan excluded files and directories during quick scans. | Microsoft Defender Antivirus STIG SCAP Benchmark

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Assessment Title

Rule Text

Microsoft Defender AV must scan excluded files and directories during quick scans.

Description

Discussion Text

In Microsoft Defender Antivirus, when an exclusion for a file or folder is created, it will generally be skipped during both real-time protection and on-demand scans (including quick scans and full scans). However, with newer releases, the option exists to configure quick scans to include files and directories that are otherwise excluded from real-time protection.

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

IA Controls

NIST SP 800-53

Not mappedCCI-002624

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:278676
# Microsoft Defender AV must scan excluded files and directories during quick scans.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# QuickScanIncludeExclusions == 1
# 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\Scan').GetValueKind('QuickScanIncludeExclusions').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Scan' -Name 'QuickScanIncludeExclusions' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'QuickScanIncludeExclusions') -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:278676
$registryPath = "HKLM:\Software\Policies\Microsoft\Windows Defender\Scan"
$registryKey = "QuickScanIncludeExclusions"
$expectedValue = 1

if (Test-Path $registryPath) {
    $registryValue = (Get-ItemProperty -Path $registryPath -Name $registryKey -ErrorAction SilentlyContinue).$registryKey
    if ($registryValue -eq $expectedValue) {
        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 >> Scan >> Scan excluded files and directories during quick scans to "Enabled".