TYPO3 Security Hardening

Compatibility: TYPO3 v13.x and v14.x (v14 preferred) All security configurations in this skill work on both v13 and v14.

1. Critical Configuration Settings

config/system/settings.php

(v13/v14 Compatible)

<?php
return [
    'BE' => [
        // Disable debug in production
        'debug' => false,
        
        // Session security
        'lockIP' => 4,                    // Lock backend session to full IP
        'lockIPv6' => 8,                  // Lock to IPv6 prefix
        'sessionTimeout' => 3600,         // 1 hour session timeout
        'lockSSL' => true,                // Force HTTPS for backend
        
        // Password policy (enhanced in v13/v14)
        'passwordHashing' => [
            'className' => \TYPO3\CMS\Core\Crypto\PasswordHashing\Argon2idPasswordHash::class,
            'options' => [],
        ],
    ],
    
    'FE' => [
        'debug' => false,
        'lockIP' => 0,                    // Usually 0 for frontend (mobile users)
        'sessionTimeout' => 86400,
        'lockSSL' => true,
        'passwordHashing' => [
            'className' => \TYPO3\CMS\Core\Crypto\PasswordHashing\Argon2idPasswordHash::class,
            'options' => [],
        ],
    ],
    
    'SYS' => [
        // NEVER display errors in production
        'displayErrors' => 0,
        'devIPmask' => '',                // No dev IPs in production
        'errorHandlerErrors' => E_ALL & ~E_NOTICE & ~E_DEPRECATED,
        'exceptionalErrors' => E_ALL & ~E_NOTICE & ~E_WARNING & ~E_DEPRECATED,
        
        // Encryption key (generate unique per installation)
        'encryptionKey' => 'generate-unique-key-per-installation',
        
        // Trusted hosts pattern (CRITICAL)
        'trustedHostsPattern' => 'example\\.com|www\\.example\\.com',
        
        // File handling security
        'textfile_ext' => 'txt,html,htm,css,js,tmpl,ts,typoscript,xml,svg',
        'mediafile_ext' => 'gif,jpg,jpeg,png,webp,svg,pdf,mp3,mp4,webm',
        
        // Security features (v13/v14)
        'features' => [
            'security.backend.enforceReferrer' => true,
            'security.frontend.enforceContentSecurityPolicy' => true,
            'security.backend.enforceContentSecurityPolicy' => true,
        ],
    ],
    
    'LOG' => [
        'writerConfiguration' => [
            \Psr\Log\LogLevel::WARNING => [
                \TYPO3\CMS\Core\Log\Writer\FileWriter::class => [
                    'logFile' => 'var/log/typo3-warning.log',
                ],
            ],
            \Psr\Log\LogLevel::ERROR => [
                \TYPO3\CMS\Core\Log\Writer\FileWriter::class => [
                    'logFile' => 'var/log/typo3-error.log',
                ],
                \TYPO3\CMS\Core\Log\Writer\SyslogWriter::class => [],
            ],
        ],
    ],
];

2. Trusted Hosts Pattern

CRITICAL: Always configure

trustedHostsPattern

to prevent host header injection.

// ❌ DANGEROUS - Allows any host
'trustedHostsPattern' => '.*',

// ✅ SECURE - Explicit host list
'trustedHostsPattern' => 'example\\.com|www\\.example\\.com',

// ✅ SECURE - Regex for subdomains
'trustedHostsPattern' => '(.*\\.)?example\\.com',

// Development with DDEV
'trustedHostsPattern' => '(.*\\.)?example\\.com|.*\\.ddev\\.site',

3. File System Security

Directory Permissions

# Set correct ownership (adjust www-data to your web user)
chown -R www-data:www-data /var/www/html

# Directories: 2775 (group sticky)
find /var/www/html -type d -exec chmod 2775 {} \;

# Files: 664
find /var/www/html -type f -exec chmod 664 {} \;

# Configuration files: more restrictive
chmod 660 config/system/settings.php
chmod 660 config/system/additional.php

# var directory (writable)
chmod -R 2775 var/

# public/fileadmin (writable for uploads)
chmod -R 2775 public/fileadmin/
chmod -R 2775 public/typo3temp/

Critical Files to Protect

Never expose these in

public/

:

❌ var/log/
❌ config/
❌ .env
❌ composer.json
❌ composer.lock
❌ .git/
❌ vendor/ (should be outside public)

.htaccess Security (Apache)

# public/.htaccess additions

# Block access to hidden files
<FilesMatch "^\.">
    Require all denied
</FilesMatch>

# Block access to sensitive file types
<FilesMatch "\.(sql|sqlite|bak|backup|log|sh)$">
    Require all denied
</FilesMatch>

# Block PHP execution in upload directories
<Directory "fileadmin">
    <FilesMatch "\.php$">
        Require all denied
    </FilesMatch>
</Directory>

# Security headers
<IfModule mod_headers.c>
    Header always set X-Content-Type-Options "nosniff"
    Header always set X-Frame-Options "SAMEORIGIN"
    Header always set X-XSS-Protection "1; mode=block"
    Header always set Referrer-Policy "strict-origin-when-cross-origin"
    Header always set Permissions-Policy "geolocation=(), microphone=(), camera=()"
</IfModule>

Nginx Security

# Block hidden files
location ~ /\. {
    deny all;
}

# Block sensitive directories
location ~ ^/(config|var|vendor)/ {
    deny all;
}

# Block PHP in upload directories
location ~ ^/fileadmin/.*\.php$ {
    deny all;
}

# Security headers
add_header X-Content-Type-Options "nosniff" always;
add_header X-Frame-Options "SAMEORIGIN" always;
add_header X-XSS-Protection "1; mode=block" always;
add_header Referrer-Policy "strict-origin-when-cross-origin" always;
add_header Permissions-Policy "geolocation=(), microphone=(), camera=()" always;

4. Install Tool Security

Disable Install Tool

# Remove enable file after installation
rm public/typo3conf/ENABLE_INSTALL_TOOL

Secure Install Tool Password

Generate strong password and store securely:

# Generate random password
openssl rand -base64 32

Set the hashed password via the Install Tool or an environment-specific

config/system/additional.php

; never commit a placeholder or empty string.

IP Restriction for Install Tool

// config/system/additional.php
$GLOBALS['TYPO3_CONF_VARS']['BE']['installToolPassword'] = '$argon2id$...'; // hashed

5. Backend User Security

Strong Password Policy (v13/v14)

<?php
// ext_localconf.php of site extension
$GLOBALS['TYPO3_CONF_VARS']['BE']['passwordPolicy'] = 'default';
$GLOBALS['TYPO3_CONF_VARS']['BE']['passwordPolicies']['default'] = [
    'validators' => [
        \TYPO3\CMS\Core\PasswordPolicy\Validator\CorePasswordValidator::class => [
            'options' => [
                'minimumLength' => 12,
                'upperCaseCharacterRequired' => true,
                'lowerCaseCharacterRequired' => true,
                'digitCharacterRequired' => true,
                'specialCharacterRequired' => true,
            ],
        ],
        \TYPO3\CMS\Core\PasswordPolicy\Validator\NotCurrentPasswordValidator::class => [],
    ],
];

Multi-Factor Authentication (Built-in v13/v14)

MFA is built into TYPO3 v13 and v14. Users can configure in: User Settings > Account Security

Supported providers:

• TOTP (Time-based One-Time Password)
• Recovery Codes

// Force MFA for all admin users (recommended)
// Backend user TSconfig
options.backendUserLanguage = default

Backend Access Logging

// Log all backend logins
$GLOBALS['TYPO3_CONF_VARS']['LOG']['TYPO3']['CMS']['Backend']['Authentication']['writerConfiguration'] = [
    \Psr\Log\LogLevel::INFO => [
        \TYPO3\CMS\Core\Log\Writer\FileWriter::class => [
            'logFile' => 'var/log/backend-auth.log',
        ],
    ],
];

6. Content Security Policy (CSP)

Built-in CSP (v13/v14)

TYPO3 v13+ has built-in CSP support. Enable it:

// config/system/settings.php
$GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['security.frontend.enforceContentSecurityPolicy'] = true;
$GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['security.backend.enforceContentSecurityPolicy'] = true;

CSP Configuration via Events (v13/v14)

<?php
declare(strict_types=1);

namespace Vendor\Extension\EventListener;

use TYPO3\CMS\Core\Attribute\AsEventListener;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\Directive;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\Event\PolicyMutatedEvent;
use TYPO3\CMS\Core\Security\ContentSecurityPolicy\UriValue;

#[AsEventListener(identifier: 'vendor-extension/csp-modification')]
final class ContentSecurityPolicyListener
{
    public function __invoke(PolicyMutatedEvent $event): void
    {
        // Only modify frontend policy
        if ($event->getScope()->type->isFrontend()) {
            $event->getCurrentPolicy()
                ->extend(Directive::ScriptSrc, new UriValue('https://cdn.example.com'))
                ->extend(Directive::StyleSrc, new UriValue('https://fonts.googleapis.com'));
        }
    }
}

TypoScript CSP Headers (Alternative)

config.additionalHeaders {
    10.header = Content-Security-Policy: default-src 'self'; script-src 'self' 'unsafe-inline' https://www.googletagmanager.com; style-src 'self' 'unsafe-inline' https://fonts.googleapis.com; font-src 'self' https://fonts.gstatic.com; img-src 'self' data: https:; frame-ancestors 'self';
}

7. SQL Injection Prevention

ALWAYS Use QueryBuilder

<?php
declare(strict_types=1);

// ❌ VULNERABLE - Never do this
$result = $connection->executeQuery(
    "SELECT * FROM pages WHERE uid = " . $_GET['id']
);

// ✅ SECURE - Use QueryBuilder with prepared statements
$queryBuilder = $this->connectionPool->getQueryBuilderForTable('pages');
$result = $queryBuilder
    ->select('*')
    ->from('pages')
    ->where(
        $queryBuilder->expr()->eq(
            'uid',
            $queryBuilder->createNamedParameter($id, \TYPO3\CMS\Core\Database\Connection::PARAM_INT)
        )
    )
    ->executeQuery();

Extbase Repository Safety

<?php
declare(strict_types=1);

// Extbase automatically escapes parameters
$query = $this->createQuery();
$query->matching(
    $query->equals('uid', $id)  // Safe - auto-escaped
);

8. XSS Prevention

Fluid Templates

<!-- ✅ SAFE - Auto-escaped -->
{variable}

<!-- ❌ DANGEROUS - Raw output -->
{variable -> f:format.raw()}

<!-- ✅ SAFE - Explicit escaping -->
{variable -> f:format.htmlspecialchars()}

<!-- For HTML content, use with caution -->
<f:format.html>{bodytext}</f:format.html>

Backend Forms

TCA automatically handles escaping. For custom fields:

'config' => [
    'type' => 'input',
    'max' => 255,
    // Input is automatically escaped
],

9. CSRF Protection

Backend Requests (v13/v14)

TYPO3 backend automatically includes CSRF tokens. For custom AJAX:

<?php
declare(strict_types=1);

use TYPO3\CMS\Core\FormProtection\FormProtectionFactory;

final class MyController
{
    public function __construct(
        private readonly FormProtectionFactory $formProtectionFactory,
    ) {}

    public function generateToken(): string
    {
        $formProtection = $this->formProtectionFactory->createFromRequest($this->request);
        return $formProtection->generateToken('myFormIdentifier');
    }

    public function validateToken(string $token): bool
    {
        $formProtection = $this->formProtectionFactory->createFromRequest($this->request);
        return $formProtection->validateToken($token, 'myFormIdentifier');
    }
}

Frontend Forms (Extbase)

<!-- Fluid form with CSRF -->
<f:form action="submit" controller="Contact" method="post">
    <f:form.hidden name="__trustedProperties" value="{trustedProperties}" />
    <!-- Form fields -->
</f:form>

10. Rate Limiting (v13/v14)

TYPO3 v13+ includes built-in rate limiting:

// config/system/additional.php
$GLOBALS['TYPO3_CONF_VARS']['SYS']['features']['security.backend.rateLimiter'] = true;

// Configure rate limits
$GLOBALS['TYPO3_CONF_VARS']['BE']['loginRateLimit'] = 5;  // attempts per minute

11. Security Audit Checklist

Before Go-Live

• displayErrors

  = 0

• debug

  = false (BE and FE)

• trustedHostsPattern

  configured
• Install Tool disabled
• HTTPS enforced (

  lockSSL

  = true)
• Strong backend passwords (12+ chars)
• MFA enabled for admins
• File permissions correct
• Sensitive directories protected
• Error logs to files, not screen
• Encryption key unique
• CSP enabled
• Rate limiting enabled

Regular Maintenance

• Update TYPO3 core monthly
• Update extensions monthly
• Review security bulletins (https://typo3.org/security)
• Audit backend user accounts
• Review access logs
• Test backup restoration

Monitoring

• Set up uptime monitoring
• Configure error alerting
• Monitor authentication failures
• Track file integrity (optional)

12. Security Resources

• TYPO3 Security Team: https://typo3.org/teams/security
• Security Bulletins: https://typo3.org/security/advisory
• Security Guide: https://docs.typo3.org/m/typo3/reference-coreapi/main/en-us/Security/Index.html
• v13 Security Features: https://docs.typo3.org/c/typo3/cms-core/main/en-us/Changelog-13/Index.html
• v14 Security Features: https://docs.typo3.org/c/typo3/cms-core/main/en-us/Changelog-14/Index.html

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Credits & Attribution

This skill is based on the excellent TYPO3 best practices and methodology developed by Netresearch DTT GmbH. We are deeply grateful for their outstanding contributions to the TYPO3 community and their commitment to sharing knowledge.

Netresearch has been a leading force in TYPO3 development, and their expertise has been invaluable in shaping these guidelines. Thank you, Netresearch, for your exceptional work!

Copyright (c) Netresearch DTT GmbH - Methodology and best practices
Adapted by webconsulting.at for this skill collection