[REQ-PAW-061] Enable EDR in Block Mode for PAWs

Target Scope

• Applicable Systems: Privileged Access Workstations (PAWs) used for Tier 0 directory administration.
• Operating Systems: Windows 10 Enterprise (1607+) and Windows 11 Enterprise.

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)

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

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

Download Script: Configure-PawDefenderEdrBlockMode.ps1

# Configure-PawDefenderEdrBlockMode.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-PawDefenderEdrBlockModeStatus.ps1

# Get-PawDefenderEdrBlockModeStatus.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 Privileged Access Workstations