[REQ-DC-078] Configure Auto Exclusions Configuration on Domain Controllers

Target Scope

• Applicable Systems: Domain Controllers.
• Operating Systems: Windows Server 2016 (and above).

Implementation Details

• Priority: Medium
• GPO Path / Registry Location:
  • GPO Path: Computer Configuration\Administrative Templates\Windows Components\Windows Defender Antivirus\Exclusions
  • Registry Location:
    • HKLM\SOFTWARE\Policies\Microsoft\Windows Defender\Exclusions
      • DisableAutoExclusions = 0 (REG_DWORD)

Rationale

Auto Exclusions automatically configure exclusions for known safe system folders or server roles to reduce performance overhead. Enforcing that auto exclusions are not disabled ensures server performance stability and proper system scanning.

Legacy Impact & Compatibility

None.

Implementation Steps

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

1. Navigate to: Computer Configuration\Administrative Templates\Windows Components\Windows Defender Antivirus\Exclusions
2. Set 'Turn off Auto Exclusions' to 'Disabled'

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

Download Script: Configure-DefenderAutoExclusions.ps1

# Configure-DefenderAutoExclusions.ps1
$ExclPath = "HKLM:\SOFTWARE\Policies\Microsoft\Windows Defender\Exclusions"
if (-not (Test-Path $ExclPath)) { New-Item -Path $ExclPath -Force | Out-Null }
Set-ItemProperty -Path $ExclPath -Name "DisableAutoExclusions" -Value 0 -Type DWord -Force

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

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

Sources & Compliance References

• CIS Microsoft Windows Server Benchmark: Section 18.9 (Windows Defender Antivirus configuration parameters)
• ANSSI Active Directory Hardening Guide: Protective controls baselines on Domain Controllers