[REQ-END-062] Enable EDR in Block Mode

Target Scope

Applicable Systems: Tier 2 client workstations and member servers.
Operating Systems: Windows 10 (and above) Enterprise/Professional, Windows Server 2016 (and above).

Implementation Details

Priority: High
GPO Path / Registry Location:
- GPO Path: Computer Configuration\Administrative Templates\Windows Components\Windows Defender Antivirus\Features
- Registry Location:
  - HKLM\SOFTWARE\Policies\Microsoft\Windows Defender\Features
    - PassiveRemediation = 1 (REG_DWORD)

Rationale

Endpoint Detection and Response (EDR) in Block Mode allows Defender to take remediation actions on malicious artifacts detected by Microsoft Defender for Endpoint even if another non-Microsoft antivirus is primary. This establishes secondary defensive block capabilities.

Legacy Impact & Compatibility

None. Extends passive monitoring to execute block operations when necessary.

Implementation Steps

Option A: Group Policy Object (GPO) Configuration (Preferred)

Navigate to: Computer Configuration\Administrative Templates\Windows Components\Windows Defender Antivirus\Features
Set 'Enable EDR in block mode' to 'Enabled'

Option B: PowerShell & Registry Configuration (Remediation / Non-GPO)

Download Script: Configure-DefenderEdrBlockMode.ps1

# Configure-DefenderEdrBlockMode.ps1
$FeaturesPath = "HKLM:\SOFTWARE\Policies\Microsoft\Windows Defender\Features"
if (-not (Test-Path $FeaturesPath)) { New-Item -Path $FeaturesPath -Force | Out-Null }
Set-ItemProperty -Path $FeaturesPath -Name "PassiveRemediation" -Value 1 -Type DWord -Force

To audit the hardening status: Download Script: Get-DefenderEdrBlockModeStatus.ps1

# Get-DefenderEdrBlockModeStatus.ps1
$Reg = Get-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows Defender\Features" -Name "PassiveRemediation" -ErrorAction SilentlyContinue
if ($Reg -and $Reg.PassiveRemediation -eq 1) {
    Write-Output "Compliant"
    exit 0
} else {
    Write-Output "Non-Compliant"
    exit 1
}

Sources & Compliance References

CIS Microsoft Windows 10 Benchmark: Section 18.9 (Windows Defender Antivirus configuration parameters)
ANSSI Active Directory Hardening Guide: Protective controls baselines on client workstations

REQ-END-062 - Enable EDR in Block Mode