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windows-hardening

Harden Windows servers per security baselines and CIS benchmarks. Configure Group Policy, Windows Defender, and security features. Use when securing Windows Server environments.
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updated2026-11-02 21:38:45

Windows Hardening

Secure Windows servers following Microsoft security baselines and CIS benchmarks.

Prerequisites

  • Windows Server 2019 or later (2022 recommended)
  • Only the least privilege required for the approved host/policy; Domain Admin is not a default prerequisite.
  • PowerShell 5.1+ (built into Windows Server)
  • Group Policy Management Console for domain environments
  • Microsoft Security Compliance Toolkit (recommended)

Security Baseline Deployment

# Download and apply Microsoft Security Baseline
# Download from: https://www.microsoft.com/en-us/download/details.aspx?id=55319

# These optional community DSC modules are not the Security Compliance Toolkit; review publisher/version before separate installation.
Install-Module -Name SecurityPolicyDsc -Force
Install-Module -Name AuditPolicyDsc -Force
Install-Module -Name PSDesiredStateConfiguration -Force

# Import and apply a security baseline GPO (from Security Compliance Toolkit)
# Extract the toolkit, then:
# LGPO.exe is an executable, not a PowerShell module. Verify the downloaded Microsoft binary signature and version.

# Apply local group policy from baseline
.\LGPO.exe /g ".\GPO\{baseline-gpo-guid}"

# Export current security policy for review
secedit /export /cfg C:\SecurityAudit\current-policy.inf

Account Policies

# ============================================
# Password Policy Configuration
# ============================================

# Set password policy via net accounts
# Example local-account settings only; align password expiry with current approved policy rather than blanket 90-day rotation.
net accounts /minpwlen:14 /minpwage:1 /uniquepw:24

# Or configure via PowerShell DSC
Configuration PasswordPolicy {
    Import-DscResource -ModuleName SecurityPolicyDsc

    Node localhost {
        AccountPolicy PasswordPolicy {
            Name                                = "PasswordPolicy"
            Minimum_Password_Length              = 14
            Maximum_Password_Age                = 0  # illustrative no periodic expiry; current baseline/incident policy governs
            Minimum_Password_Age                = 1
            Enforce_password_history             = 24
            Password_must_meet_complexity_requirements = "Enabled"
            Store_passwords_using_reversible_encryption = "Disabled"
        }
    }
}

# ============================================
# Account Lockout Policy
# ============================================
net accounts /lockoutthreshold:5 /lockoutwindow:30 /lockoutduration:30

# ============================================
# User Account Hardening
# ============================================

# Rename and disable default accounts
Rename-LocalUser -Name "Administrator" -NewName "LocalAdmin"
Disable-LocalUser -Name "Guest"
Disable-LocalUser -Name "DefaultAccount"

# Remove unnecessary local accounts
$unnecessaryAccounts = Get-LocalUser | Where-Object {
    $_.Enabled -eq $true -and
    $_.Name -notin @("LocalAdmin", "SYSTEM", "NetworkService", "LocalService")
}
foreach ($account in $unnecessaryAccounts) {
    Write-Host "Review account: $($account.Name) - Last logon: $($account.LastLogon)"
}

# Configure Local Administrator Password Solution (LAPS)
# Legacy Microsoft LAPS example only: RSAT-AD-PowerShell does not install AdmPwd.PS.
# Prefer built-in Windows LAPS with its current schema/permissions/backup policy; do not mix legacy and modern commands.
Import-Module AdmPwd.PS  # only when legacy LAPS was intentionally installed and remains supported

# Configure LAPS for the OU
Set-AdmPwdComputerSelfPermission -OrgUnit "OU=Servers,DC=example,DC=com"
Set-AdmPwdReadPasswordPermission -OrgUnit "OU=Servers,DC=example,DC=com" -AllowedPrincipals "Domain Admins"

Group Policy Security Settings

# ============================================
# User Rights Assignment (via GPO or local policy)
# ============================================

# Restrict remote desktop access
# Computer Configuration > Policies > Windows Settings > Security Settings > Local Policies > User Rights Assignment
# "Allow log on through Remote Desktop Services" = Administrators, Remote Desktop Users

# Deny log on locally for service accounts
# "Deny log on locally" = Service accounts

# Configure via registry (alternative to GPO)
# Restrict anonymous enumeration of SAM accounts
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa" `
    -Name "RestrictAnonymousSAM" -Value 1

# Restrict anonymous enumeration of shares
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa" `
    -Name "RestrictAnonymous" -Value 1

# Do not display last user name
Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" `
    -Name "DontDisplayLastUserName" -Value 1

# ============================================
# Security Options
# ============================================

# Disable SMBv1 (critical security hardening)
Disable-WindowsOptionalFeature -Online -FeatureName SMB1Protocol -NoRestart
Set-SmbServerConfiguration -EnableSMB1Protocol $false -Force

# Require SMB signing
Set-SmbServerConfiguration -RequireSecuritySignature $true -Force
Set-SmbClientConfiguration -RequireSecuritySignature $true -Force

# Disable LLMNR (prevent credential theft)
New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient" -Force
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows NT\DNSClient" `
    -Name "EnableMulticast" -Value 0

# Disable NetBIOS over TCP/IP
$adapters = Get-WmiObject Win32_NetworkAdapterConfiguration | Where-Object { $_.IPEnabled -eq $true }
foreach ($adapter in $adapters) {
    $adapter.SetTcpipNetbios(2)  # 2 = Disable
}

# Disable WDigest (prevent plaintext password caching)
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\SecurityProviders\WDigest" `
    -Name "UseLogonCredential" -Value 0

# Enable LSA Protection
Set-ItemProperty -Path "HKLM:\SYSTEM\CurrentControlSet\Control\Lsa" `
    -Name "RunAsPPL" -Value 1

# Configure UAC
Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" `
    -Name "EnableLUA" -Value 1
Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" `
    -Name "ConsentPromptBehaviorAdmin" -Value 2
Set-ItemProperty -Path "HKLM:\SOFTWARE\Microsoft\Windows\CurrentVersion\Policies\System" `
    -Name "PromptOnSecureDesktop" -Value 1

Windows Firewall Configuration

# ============================================
# Enable Windows Firewall on all profiles
# ============================================
Set-NetFirewallProfile -Profile Domain,Public,Private -Enabled True

# Default deny inbound, allow outbound
Set-NetFirewallProfile -Profile Domain -DefaultInboundAction Block -DefaultOutboundAction Allow
Set-NetFirewallProfile -Profile Public -DefaultInboundAction Block -DefaultOutboundAction Allow
Set-NetFirewallProfile -Profile Private -DefaultInboundAction Block -DefaultOutboundAction Allow

# Enable logging
Set-NetFirewallProfile -Profile Domain -LogAllowed True -LogBlocked True `
    -LogFileName "%SystemRoot%\System32\LogFiles\Firewall\pfirewall.log" `
    -LogMaxSizeKilobytes 32768

# ============================================
# Inbound Rules
# ============================================

# Allow RDP from management network only
New-NetFirewallRule -DisplayName "Allow RDP - Management" `
    -Direction Inbound -Protocol TCP -LocalPort 3389 `
    -RemoteAddress 10.0.100.0/24 -Action Allow -Profile Domain

# Allow WinRM from management network
New-NetFirewallRule -DisplayName "Allow WinRM - Management" `
    -Direction Inbound -Protocol TCP -LocalPort 5985,5986 `
    -RemoteAddress 10.0.100.0/24 -Action Allow -Profile Domain

# Allow ICMP from internal networks
New-NetFirewallRule -DisplayName "Allow ICMP - Internal" `
    -Direction Inbound -Protocol ICMPv4 -IcmpType 8 `
    -RemoteAddress 10.0.0.0/8 -Action Allow

# Allow specific application
New-NetFirewallRule -DisplayName "Allow IIS HTTPS" `
    -Direction Inbound -Protocol TCP -LocalPort 443 `
    -Action Allow -Profile Domain,Private

# Block all other inbound by default (already set above)

# ============================================
# Outbound Rules (optional - restrict egress)
# ============================================

# Allow DNS
New-NetFirewallRule -DisplayName "Allow DNS" `
    -Direction Outbound -Protocol UDP -RemotePort 53 `
    -Action Allow

# Allow HTTPS for updates
New-NetFirewallRule -DisplayName "Allow HTTPS Out" `
    -Direction Outbound -Protocol TCP -RemotePort 443 `
    -Action Allow

# Allow NTP
New-NetFirewallRule -DisplayName "Allow NTP" `
    -Direction Outbound -Protocol UDP -RemotePort 123 `
    -Action Allow

# ============================================
# Firewall Audit
# ============================================

# List all enabled firewall rules
Get-NetFirewallRule -Enabled True | Format-Table DisplayName, Direction, Action, Profile

# Export firewall rules
netsh advfirewall export "C:\SecurityAudit\firewall-rules.wfw"

# Find overly permissive rules
Get-NetFirewallRule -Enabled True -Direction Inbound -Action Allow |
    ForEach-Object {
        $rule = $_
        $address = $rule | Get-NetFirewallAddressFilter
        $port = $rule | Get-NetFirewallPortFilter
        if ($address.RemoteAddress -contains 'Any') {
            [pscustomobject]@{ DisplayName=$rule.DisplayName; LocalPort=$port.LocalPort; RemoteAddress=$address.RemoteAddress; Profile=$rule.Profile }
        }
    }

Audit Policy Configuration

# ============================================
# Advanced Audit Policy
# ============================================

# Account Logon
auditpol /set /subcategory:"Credential Validation" /success:enable /failure:enable
auditpol /set /subcategory:"Kerberos Authentication Service" /success:enable /failure:enable
auditpol /set /subcategory:"Kerberos Service Ticket Operations" /success:enable /failure:enable

# Account Management
auditpol /set /subcategory:"Computer Account Management" /success:enable
auditpol /set /subcategory:"Security Group Management" /success:enable
auditpol /set /subcategory:"User Account Management" /success:enable /failure:enable

# Logon/Logoff
auditpol /set /subcategory:"Logon" /success:enable /failure:enable
auditpol /set /subcategory:"Logoff" /success:enable
auditpol /set /subcategory:"Account Lockout" /success:enable /failure:enable
auditpol /set /subcategory:"Special Logon" /success:enable

# Object Access
auditpol /set /subcategory:"File System" /success:enable /failure:enable
auditpol /set /subcategory:"Registry" /success:enable /failure:enable
auditpol /set /subcategory:"SAM" /success:enable /failure:enable

# Policy Change
auditpol /set /subcategory:"Audit Policy Change" /success:enable /failure:enable
auditpol /set /subcategory:"Authentication Policy Change" /success:enable
auditpol /set /subcategory:"Authorization Policy Change" /success:enable

# Privilege Use
auditpol /set /subcategory:"Sensitive Privilege Use" /success:enable /failure:enable

# System
auditpol /set /subcategory:"Security State Change" /success:enable /failure:enable
auditpol /set /subcategory:"Security System Extension" /success:enable /failure:enable
auditpol /set /subcategory:"System Integrity" /success:enable /failure:enable

# Verify audit policy
auditpol /get /category:*

# Export audit policy
auditpol /backup /file:C:\SecurityAudit\audit-policy.csv

# ============================================
# PowerShell Logging (Critical for forensics)
# ============================================

# Enable Script Block Logging
New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging" -Force
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ScriptBlockLogging" `
    -Name "EnableScriptBlockLogging" -Value 1

# Enable Module Logging
New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ModuleLogging" -Force
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ModuleLogging" `
    -Name "EnableModuleLogging" -Value 1
New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ModuleLogging\ModuleNames" -Force
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\ModuleLogging\ModuleNames" `
    -Name "*" -Value "*"

# Enable Transcription Logging
New-Item -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\Transcription" -Force
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\Transcription" `
    -Name "EnableTranscripting" -Value 1
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\Transcription" `
    -Name "OutputDirectory" -Value "C:\PSLogs"
Set-ItemProperty -Path "HKLM:\SOFTWARE\Policies\Microsoft\Windows\PowerShell\Transcription" `
    -Name "EnableInvocationHeader" -Value 1

# Configure Windows Event Forwarding (WEF) for centralized logging
wecutil qc /q

Windows Defender Configuration

# ============================================
# Real-time Protection
# ============================================
Set-MpPreference -DisableRealtimeMonitoring $false
Set-MpPreference -DisableBehaviorMonitoring $false
Set-MpPreference -DisableIOAVProtection $false
Set-MpPreference -DisableScriptScanning $false

# ============================================
# Cloud Protection
# ============================================
Set-MpPreference -MAPSReporting Advanced
Set-MpPreference -SubmitSamplesConsent SendSafeSamples  # confirm privacy/data-transfer policy
Set-MpPreference -CloudBlockLevel High
Set-MpPreference -CloudExtendedTimeout 50

# ============================================
# Scan Configuration
# ============================================
Set-MpPreference -ScanScheduleDay Everyday
Set-MpPreference -ScanScheduleTime 02:00:00
Set-MpPreference -ScanParameters FullScan

# The configuration above schedules a daily full scan, not a weekly one. Choose a validated host-specific schedule.
Set-MpPreference -ScanScheduleQuickScanTime 12:00:00

# Scan removable drives
Set-MpPreference -DisableRemovableDriveScanning $false

# Scan network files
Set-MpPreference -DisableScanningNetworkFiles $false

# ============================================
# Attack Surface Reduction (ASR) Rules
# ============================================

# Block executable content from email and webmail
Add-MpPreference -AttackSurfaceReductionRules_Ids BE9BA2D9-53EA-4CDC-84E5-9B1EEEE46550 `
    -AttackSurfaceReductionRules_Actions AuditMode

# Block Office applications from creating child processes
Add-MpPreference -AttackSurfaceReductionRules_Ids D4F940AB-401B-4EFC-AADC-AD5F3C50688A `
    -AttackSurfaceReductionRules_Actions AuditMode

# Block credential stealing from LSASS
Add-MpPreference -AttackSurfaceReductionRules_Ids 9E6C4E1F-7D60-472F-BA1A-A39EF669E4B2 `
    -AttackSurfaceReductionRules_Actions AuditMode

# Block process creations from PSExec and WMI commands
Add-MpPreference -AttackSurfaceReductionRules_Ids D1E49AAC-8F56-4280-B9BA-993A6D77406C `
    -AttackSurfaceReductionRules_Actions AuditMode

# Block JavaScript and VBScript from launching downloaded content
Add-MpPreference -AttackSurfaceReductionRules_Ids D3E037E1-3EB8-44C8-A917-57927947596D `
    -AttackSurfaceReductionRules_Actions AuditMode

# Block Office macros from calling Win32 API
Add-MpPreference -AttackSurfaceReductionRules_Ids 92E97FA1-2EDF-4476-BDD6-9DD0B4DDDC7B `
    -AttackSurfaceReductionRules_Actions AuditMode

# View ASR rule status
Get-MpPreference | Select-Object -ExpandProperty AttackSurfaceReductionRules_Ids
Get-MpPreference | Select-Object -ExpandProperty AttackSurfaceReductionRules_Actions

# ============================================
# Exclusions (minimize these)
# ============================================
# Only add exclusions when absolutely necessary and document the reason
# No default exclusion: investigate/submit false positives and require a narrowly approved exception.

# Review current exclusions
Get-MpPreference | Select-Object -ExpandProperty ExclusionPath
Get-MpPreference | Select-Object -ExpandProperty ExclusionProcess
Get-MpPreference | Select-Object -ExpandProperty ExclusionExtension

# Update definitions manually
Update-MpSignature

Contents

When to Use This Skill

Use this skill when:

  • Hardening new Windows Server deployments
  • Implementing CIS benchmarks or Microsoft security baselines
  • Preparing for compliance audits (SOC2, PCI-DSS, HIPAA)
  • Configuring security features after a security incident
  • Setting up Windows Defender and advanced threat protection
  • Establishing Group Policy security standards for a domain

Limitations

  • Apply guidance only within authorized scope; test destructive steps in non-production first.
  • Docs-only import: upstream scripts and templates not bundled.

Example

# Read-only first: inventory before any active step.
which <tool> && <tool> --help | head -n 20

Adapted from BagelHole/DevOps-Security-Agent-Skills (MIT); frontmatter, When to Use/Limitations, and safety boundaries added for upstream compliance. Docs-only import: helper scripts and templates not bundled.

Deployment boundaries

These are separate version/role-specific fragments, not a safe-to-run baseline script or compliance certification. Inventory OS/build, server role, domain policy precedence and break-glass access; export protected backups before mutation and stage rollout with remote-console recovery. English account names/audit subcategories vary by locale: resolve built-in identities by SID and policy IDs. Do not rename/disable an active management identity before validating an alternate.

Creating narrow firewall allows does not override existing broad allow rules; review the effective policy before claiming network restriction. The outbound examples do not restrict egress while DefaultOutboundAction remains Allow. Audit categories need relevant SACLs and retention/forwarding capacity; logs/transcripts can capture secrets and require protected ACLs/redaction. Configure a collector/subscription for WEF; wecutil qc on its own does not create forwarding. ASR starts in audit and only enforces after compatibility review. Reboot requirements and UEFI-locked controls require explicit recovery planning. No Windows policy or script was executed.