SV-213452r1192806: Microsoft Defender AV spyware definition age must not exceed 7 days. | Microsoft Defender Antivirus STIG SCAP Benchmark

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Assessment Title

Rule Text

Microsoft Defender AV spyware definition age must not exceed 7 days.

Description

Discussion Text

This policy setting allows defining the number of days that must pass before spyware definitions are considered out of date. If definitions are determined to be out of date, this state may trigger several additional actions, including falling back to an alternative update source or displaying a warning icon in the user interface. By default this value is set to 14 days. If this setting is enabled, spyware definitions will be considered out of date after the number of days specified have passed without an update. If this setting is disabled or not configured, spyware definitions will be considered out of date after the default number of days have passed without an update.

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

IA Controls

NIST SP 800-53

Not mappedCCI-004964SV-89921V-75241

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.defenderantivirus:def:27
# Microsoft Defender AV spyware definition age must not exceed 7 days.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# Computer Configuration\Administrative Templates\Windows Components\Microsoft Defender Antivirus\Signature Updates\Define the number of days before spyware definitions are considered out of date is set to 7 days or less
# 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\Signature Updates').GetValueKind('ASSignatureDue').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Signature Updates' -Name 'ASSignatureDue' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'ASSignatureDue') -le 7))
}
# Computer Configuration\Administrative Templates\Windows Components\Microsoft Defender Antivirus\Signature Updates\Define the number of days before spyware definitions are considered out of date is not set to 0
# 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 Defender\Signature Updates').GetValueKind('ASSignatureDue').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Signature Updates' -Name 'ASSignatureDue' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'ASSignatureDue') -gt 0))
}

if ((test_1 -and 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_defender_antivirus target this check assesses.

# OVAL Definition: oval:mil.disa.stig.defenderantivirus:def:27
$compliant = (Get-ItemProperty -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Signature Updates' -ErrorAction SilentlyContinue -Name 'ASSignatureDue' -ValueOnly).ASSignatureDue -le 7 -and (Get-ItemProperty -Path 'HKLM:\Software\Policies\Microsoft\Windows Defender\Signature Updates' -ErrorAction SilentlyContinue -Name 'ASSignatureDue' -ValueOnly).ASSignatureDue -ne 0
if ($compliant) { Write-Output "PASS"; Exit 0 } else { Write-Output "FAIL"; Exit 1 }

Remediation

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Windows Defender Antivirus >> Signature Updates >> "Define the number of days before spyware definitions are considered out of date" to "Enabled" and select "7" or less in the drop-down box.

Do not select a value of 0. This disables the option.