Security Guidelines

Overview

This document outlines security best practices for XOOPS development, covering input validation, output encoding, authentication, authorization, and protection against common web vulnerabilities.

Security Principles

flowchart TB
    subgraph "Defense in Depth"
        A[Input Validation] --> B[Authentication]
        B --> C[Authorization]
        C --> D[Data Sanitization]
        D --> E[Output Encoding]
        E --> F[Audit Logging]
    end

Input Validation

Request Sanitization

use Xoops\Core\Request;

// Always use typed getters
$id = Request::getInt('id', 0, 'GET');
$name = Request::getString('name', '', 'POST');
$email = Request::getEmail('email', '', 'POST');
$url = Request::getUrl('website', '', 'POST');

// Never use raw $_GET/$_POST/$_REQUEST
// Bad: $id = $_GET['id'];
// Good: $id = Request::getInt('id', 0, 'GET');

Validation Rules

// Validate before use
if ($id <= 0) {
    throw new InvalidArgumentException('Invalid ID');
}

if (!preg_match('/^[a-zA-Z0-9_]{3,50}$/', $username)) {
    throw new InvalidArgumentException('Invalid username format');
}

// Use whitelist validation for enums
$allowedStatuses = ['draft', 'published', 'archived'];
if (!in_array($status, $allowedStatuses, true)) {
    throw new InvalidArgumentException('Invalid status');
}

SQL Injection Prevention

Use Parameterized Queries

// GOOD: Parameterized query
$sql = "SELECT * FROM {$xoopsDB->prefix('users')} WHERE uid = ?";
$result = $xoopsDB->query($sql, [$userId]);

// BAD: String concatenation (vulnerable!)
// $sql = "SELECT * FROM users WHERE uid = " . $userId;

Using Criteria Objects

use Criteria;
use CriteriaCompo;

$criteria = new CriteriaCompo();
$criteria->add(new Criteria('status', 'published'));
$criteria->add(new Criteria('uid', $userId, '='));
$criteria->add(new Criteria('created', time() - 86400, '>'));

$articles = $articleHandler->getObjects($criteria);

XSS Prevention

Output Encoding

use Xoops\Core\Text\Sanitizer;

// HTML context
$safeName = htmlspecialchars($userName, ENT_QUOTES, 'UTF-8');

// In templates (auto-escaped)
{$userName|escape}

// For rich content
$sanitizer = Sanitizer::getInstance();
$safeContent = $sanitizer->sanitizeForDisplay($content);

Content Security Policy

// Set CSP headers
header("Content-Security-Policy: default-src 'self'; script-src 'self'; style-src 'self' 'unsafe-inline'");

CSRF Protection

Token Implementation

// Generate token
use Xoops\Core\Security;

$token = Security::createToken();

// In form
echo '<input type="hidden" name="XOOPS_TOKEN_REQUEST" value="' . $token . '">';

// Verify on submission
if (!Security::checkToken()) {
    die('Security token mismatch');
}

Using XoopsForm

// Automatically adds CSRF token
$form = new XoopsThemeForm('Edit Article', 'articleform', 'save.php');
$form->addElement(new XoopsFormHiddenToken());

Authentication

Password Handling

// Hash passwords (PHP 5.5+)
$hashedPassword = password_hash($plainPassword, PASSWORD_ARGON2ID);

// Verify passwords
if (password_verify($plainPassword, $storedHash)) {
    // Password correct
}

// Check if rehash needed
if (password_needs_rehash($storedHash, PASSWORD_ARGON2ID)) {
    $newHash = password_hash($plainPassword, PASSWORD_ARGON2ID);
    // Update stored hash
}

Session Security

// Regenerate session ID after login
session_regenerate_id(true);

// Set secure session cookie options
ini_set('session.cookie_httponly', 1);
ini_set('session.cookie_secure', 1);
ini_set('session.cookie_samesite', 'Lax');

Authorization

Permission Checks

// Check module admin
if (!$xoopsUser || !$xoopsUser->isAdmin($xoopsModule->mid())) {
    redirect_header('index.php', 3, 'Access denied');
}

// Check group permissions
$grouppermHandler = xoops_getHandler('groupperm');
$groups = $xoopsUser ? $xoopsUser->getGroups() : [XOOPS_GROUP_ANONYMOUS];

if (!$grouppermHandler->checkRight('view_item', $itemId, $groups, $moduleId)) {
    throw new AccessDeniedException('Permission denied');
}

Role-Based Access

class PermissionChecker
{
    public function canEdit(Article $article, ?XoopsUser $user): bool
    {
        if (!$user) {
            return false;
        }

        // Admin can edit anything
        if ($user->isAdmin()) {
            return true;
        }

        // Author can edit their own
        if ($article->getAuthorId() === $user->uid()) {
            return true;
        }

        // Check editor permission
        return $this->hasPermission($user, 'article_edit');
    }
}

File Upload Security

class SecureUploader
{
    private array $allowedMimeTypes = [
        'image/jpeg',
        'image/png',
        'image/gif'
    ];

    private array $allowedExtensions = ['jpg', 'jpeg', 'png', 'gif'];

    public function validate(array $file): bool
    {
        // Check file size
        if ($file['size'] > 2 * 1024 * 1024) {
            throw new FileTooLargeException();
        }

        // Verify MIME type
        $finfo = new finfo(FILEINFO_MIME_TYPE);
        $mimeType = $finfo->file($file['tmp_name']);

        if (!in_array($mimeType, $this->allowedMimeTypes, true)) {
            throw new InvalidFileTypeException();
        }

        // Check extension
        $extension = strtolower(pathinfo($file['name'], PATHINFO_EXTENSION));
        if (!in_array($extension, $this->allowedExtensions, true)) {
            throw new InvalidFileTypeException();
        }

        // Generate safe filename
        return true;
    }

    public function generateSafeFilename(string $original): string
    {
        $extension = strtolower(pathinfo($original, PATHINFO_EXTENSION));
        return bin2hex(random_bytes(16)) . '.' . $extension;
    }
}

Audit Logging

class SecurityLogger
{
    public function logAuthAttempt(string $username, bool $success, string $ip): void
    {
        $data = [
            'username' => $username,
            'success' => $success,
            'ip' => $ip,
            'user_agent' => $_SERVER['HTTP_USER_AGENT'] ?? '',
            'timestamp' => time()
        ];

        // Log to database or file
        $this->log('auth', $data);
    }

    public function logSensitiveAction(int $userId, string $action, array $context): void
    {
        $data = [
            'user_id' => $userId,
            'action' => $action,
            'context' => json_encode($context),
            'ip' => $_SERVER['REMOTE_ADDR'],
            'timestamp' => time()
        ];

        $this->log('audit', $data);
    }
}

Security Headers

// Recommended security headers
header('X-Content-Type-Options: nosniff');
header('X-Frame-Options: SAMEORIGIN');
header('X-XSS-Protection: 1; mode=block');
header('Referrer-Policy: strict-origin-when-cross-origin');
header('Permissions-Policy: geolocation=(), microphone=(), camera=()');

// HSTS (only for HTTPS sites)
if (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on') {
    header('Strict-Transport-Security: max-age=31536000; includeSubDomains');
}

Rate Limiting

class RateLimiter
{
    public function check(string $key, int $maxAttempts, int $windowSeconds): bool
    {
        $cacheKey = 'rate_limit:' . $key;
        $attempts = (int) $this->cache->get($cacheKey, 0);

        if ($attempts >= $maxAttempts) {
            return false; // Rate limited
        }

        $this->cache->increment($cacheKey, 1, $windowSeconds);
        return true;
    }
}

// Usage
$limiter = new RateLimiter();
if (!$limiter->check('login:' . $ip, 5, 300)) {
    throw new TooManyRequestsException('Too many login attempts');
}

Security Checklist

Authentication System
Permission System
Input Validation

Security Guidelines

Overview

Security Principles

Input Validation

Request Sanitization

Validation Rules

SQL Injection Prevention

Use Parameterized Queries

Using Criteria Objects

XSS Prevention

Output Encoding

Content Security Policy

CSRF Protection

Token Implementation

Using XoopsForm

Authentication

Password Handling

Session Security

Authorization

Permission Checks

Role-Based Access

File Upload Security

Audit Logging

Security Headers

Rate Limiting

Security Checklist

Related Documentation