SV-278675r1192827: Microsoft Defender AV must report Dynamic Signature dropped events. | Microsoft Defender Antivirus STIG SCAP Benchmark

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Assessment Title

Rule Text

Microsoft Defender AV must report Dynamic Signature dropped events.

Description

Discussion Text

Microsoft Defender Antivirus logs "Dynamic Signature dropped" events when it blocks or removes a file based on a dynamically updated signature, but the signature itself is dropped, meaning it was not fully processed or applied. This can indicate a potential issue with signature updates or the system's ability to handle them.

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:278675
# Microsoft Defender AV must report Dynamic Signature dropped events.
# Per-module read mechanism curated from static teardown of DISA's SCC tool
# (SCAP Compliance Checker) -- see the SCC Automation Reference above.

# EnableDynamicSignatureDroppedEventReporting == 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\Reporting').GetValueKind('EnableDynamicSignatureDroppedEventReporting').ToString()]) -eq 'reg_dword') -and (((Get-ItemProperty -Path 'Registry::HKEY_LOCAL_MACHINE\Software\Policies\Microsoft\Windows Defender\Reporting' -Name 'EnableDynamicSignatureDroppedEventReporting' -ErrorAction SilentlyContinue) | Select-Object -ExpandProperty 'EnableDynamicSignatureDroppedEventReporting') -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:278675
$compliant = Test-Path -Path "HKLM:\Software\Policies\Microsoft\Windows Defender\Reporting" -and (Get-ItemProperty -Path "HKLM:\Software\Policies\Microsoft\Windows Defender\Reporting" -Name EnableDynamicSignatureDroppedEventReporting -ErrorAction SilentlyContinue).EnableDynamicSignatureDroppedEventReporting -eq 1
if ($compliant) { Write-Output "PASS"; Exit 0 } else { Write-Output "FAIL"; Exit 1 }

Remediation

Set the policy value for Computer Configuration >> Administrative Templates >> Windows Components >> Microsoft Defender Antivirus >> Reporting >> Configure whether to report Dynamic Signature dropped events to "Enabled".