[REQ-DC-142] Audit Policy: Object Access Auditing on Domain Controllers

Target Scope

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

Implementation Details

• Priority: High
• GPO Path / Registry Location:
  • GPO Paths: Computer Configuration\Policies\Windows Settings\Security Settings\Advanced Audit Policy Configuration\Audit Policies
  • Subcategory: Handle Manipulation -> Success and Failure
  • Subcategory: Registry -> Success and Failure
  • Subcategory: File Share -> Success and Failure
  • Subcategory: Detailed File Share -> Failure
  • Subcategory: Other Object Access Events -> Success and Failure

Rationale

Auditing object access (files, registry keys, and shares) helps monitor unauthorized modifications to system configuration files and access to restricted shares.

Legacy Impact & Compatibility

• Event Log Volume: Verify that the local Security Event Log size is set to a minimum of 1GB on Domain Controllers to prevent rapid log rollover.

Implementation Steps

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

1. Configure Advanced Audit Policy subcategory or registry override preferences matching:
   • Subcategory: Handle Manipulation -> Success and Failure
   • Subcategory: Registry -> Success and Failure
   • Subcategory: File Share -> Success and Failure
   • Subcategory: Detailed File Share -> Failure
   • Subcategory: Other Object Access Events -> Success and Failure

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

Download Script: Configure-DcAuditObjectaccess.ps1

# Configure-DcAuditObjectaccess.ps1
Write-Host "Applying Audit Policy category: object-access..." -ForegroundColor Cyan

# Set Audit Subcategory: Handle Manipulation
$Process = Start-Process auditpol -ArgumentList "/set /subcategory:`"Handle Manipulation`" /success:enable /failure:enable" -Wait -NoNewWindow -PassThru
if ($Process.ExitCode -eq 0) {
    Write-Host "    Enforced subcategory Handle Manipulation to Success and Failure" -ForegroundColor Green
} else {
    Write-Error "    Failed to configure subcategory Handle Manipulation. Exit Code: $($Process.ExitCode)"
}

# Set Audit Subcategory: Registry
$Process = Start-Process auditpol -ArgumentList "/set /subcategory:`"Registry`" /success:enable /failure:enable" -Wait -NoNewWindow -PassThru
if ($Process.ExitCode -eq 0) {
    Write-Host "    Enforced subcategory Registry to Success and Failure" -ForegroundColor Green
} else {
    Write-Error "    Failed to configure subcategory Registry. Exit Code: $($Process.ExitCode)"
}

# Set Audit Subcategory: File Share
$Process = Start-Process auditpol -ArgumentList "/set /subcategory:`"File Share`" /success:enable /failure:enable" -Wait -NoNewWindow -PassThru
if ($Process.ExitCode -eq 0) {
    Write-Host "    Enforced subcategory File Share to Success and Failure" -ForegroundColor Green
} else {
    Write-Error "    Failed to configure subcategory File Share. Exit Code: $($Process.ExitCode)"
}

# Set Audit Subcategory: Detailed File Share
$Process = Start-Process auditpol -ArgumentList "/set /subcategory:`"Detailed File Share`" /success:disable /failure:enable" -Wait -NoNewWindow -PassThru
if ($Process.ExitCode -eq 0) {
    Write-Host "    Enforced subcategory Detailed File Share to Failure" -ForegroundColor Green
} else {
    Write-Error "    Failed to configure subcategory Detailed File Share. Exit Code: $($Process.ExitCode)"
}

# Set Audit Subcategory: Other Object Access Events
$Process = Start-Process auditpol -ArgumentList "/set /subcategory:`"Other Object Access Events`" /success:enable /failure:enable" -Wait -NoNewWindow -PassThru
if ($Process.ExitCode -eq 0) {
    Write-Host "    Enforced subcategory Other Object Access Events to Success and Failure" -ForegroundColor Green
} else {
    Write-Error "    Failed to configure subcategory Other Object Access Events. Exit Code: $($Process.ExitCode)"
}

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

# Get-DcAuditObjectaccessStatus.ps1
$script:Vulnerable = $false

# Audit Subcategory: Handle Manipulation
$RawOutput = auditpol.exe /get /subcategory:"Handle Manipulation" /r
if ($RawOutput -notmatch ",Handle Manipulation,.*,(Success and Failure|Success & Failure)") {
    $script:Vulnerable = $true
}

# Audit Subcategory: Registry
$RawOutput = auditpol.exe /get /subcategory:"Registry" /r
if ($RawOutput -notmatch ",Registry,.*,(Success and Failure|Success & Failure)") {
    $script:Vulnerable = $true
}

# Audit Subcategory: File Share
$RawOutput = auditpol.exe /get /subcategory:"File Share" /r
if ($RawOutput -notmatch ",File Share,.*,(Success and Failure|Success & Failure)") {
    $script:Vulnerable = $true
}

# Audit Subcategory: Detailed File Share
$RawOutput = auditpol.exe /get /subcategory:"Detailed File Share" /r
if ($RawOutput -notmatch ",Detailed File Share,.*,Failure") {
    $script:Vulnerable = $true
}

# Audit Subcategory: Other Object Access Events
$RawOutput = auditpol.exe /get /subcategory:"Other Object Access Events" /r
if ($RawOutput -notmatch ",Other Object Access Events,.*,(Success and Failure|Success & Failure)") {
    $script:Vulnerable = $true
}

if ($script:Vulnerable) {
    Write-Output "Non-Compliant"
    exit 1
} else {
    Write-Output "Compliant"
    exit 0
}

Sources & Compliance References

• ANSSI Active Directory Hardening Guide: Recommendation R48
• CIS Windows Server Benchmark: Section 9 (Audit Policy)