SV-278677r1192829: Microsoft Defender AV must convert warn verdict to block. | Microsoft Defender Antivirus STIG SCAP Benchmark

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Assessment Title

Rule Text

Microsoft Defender AV must convert warn verdict to block.

Description

Discussion Text

If a site URL has an unknown or uncertain reputation, a toast notification presents the user with the following options: - Ok: The toast notification is released (removed), and the attempt to access the site is ended. - Unblock: The user has access to the site for 24 hours, at which point the block is reenabled. The user can continue to use Unblock to access the site until such time that the administrator prohibits (blocks) the site, thus removing the option to Unblock. - Feedback: The toast notification presents the user with a link to submit a ticket, which the user can use to submit feedback to the administrator in an attempt to justify access to the site.

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:278677
# Microsoft Defender AV must convert warn verdict to block.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# EnableConvertWarnToBlock == 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\NIS').GetValueKind('EnableConvertWarnToBlock').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\NIS' -Name 'EnableConvertWarnToBlock' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'EnableConvertWarnToBlock') -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:mil.disa.stig.windowsdefav:def:278677
if (Test-Path -Path "HKLM:\Software\Policies\Microsoft\Windows Defender\NIS" -ErrorAction SilentlyContinue) { $regValue = Get-ItemProperty -Path "HKLM:\Software\Policies\Microsoft\Windows Defender\NIS" -Name "EnableConvertWarnToBlock" -ErrorAction SilentlyContinue; if ($regValue -and $regValue.EnableConvertWarnToBlock -eq 1) { 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 >> Network Inspection System >> Convert warn verdict to block to "Enabled".