Adds security headers include middleware

app/includes/security_headers_middleware.php

@@ -0,0 +1,72 @@
+<?php
+
+/**
+ * Security Headers Middleware
+ * 
+ * Sets various security headers to protect against common web vulnerabilities:
+ * - HSTS: Force HTTPS connections
+ * - CSP: Content Security Policy to prevent XSS and other injection attacks
+ * - X-Frame-Options: Prevent clickjacking
+ * - X-Content-Type-Options: Prevent MIME-type sniffing
+ * - Referrer-Policy: Control referrer information
+ * - Permissions-Policy: Control browser features
+ */
+
+// Strict Transport Security (HSTS)
+// Only enable if HTTPS is properly configured
+if (isset($_SERVER['HTTPS']) && $_SERVER['HTTPS'] === 'on') {
+    header('Strict-Transport-Security: max-age=31536000; includeSubDomains; preload');
+}
+
+// Content Security Policy (CSP)
+$csp = [
+    "default-src 'self'",
+    "script-src 'self' 'unsafe-inline' 'unsafe-eval'", // Required for Bootstrap and jQuery
+    "style-src 'self' 'unsafe-inline'", // Required for Bootstrap
+    "img-src 'self' data:", // Allow data: URLs for images
+    "font-src 'self'",
+    "connect-src 'self'",
+    "frame-ancestors 'none'", // Equivalent to X-Frame-Options: DENY
+    "form-action 'self'",
+    "base-uri 'self'",
+    "upgrade-insecure-requests" // Force HTTPS for all requests
+];
+header("Content-Security-Policy: " . implode('; ', $csp));
+
+// X-Frame-Options (legacy support)
+header('X-Frame-Options: DENY');
+
+// X-Content-Type-Options
+header('X-Content-Type-Options: nosniff');
+
+// Referrer-Policy
+header('Referrer-Policy: strict-origin-when-cross-origin');
+
+// Permissions-Policy
+$permissions = [
+    'geolocation=()',
+    'microphone=()',
+    'camera=()',
+    'payment=()',
+    'usb=()',
+    'accelerometer=()',
+    'autoplay=()',
+    'document-domain=()',
+    'encrypted-media=()',
+    'fullscreen=(self)',
+    'magnetometer=()',
+    'midi=()',
+    'sync-xhr=(self)',
+    'usb=()'
+];
+header('Permissions-Policy: ' . implode(', ', $permissions));
+
+// Clear PHP version
+header_remove('X-Powered-By');
+
+// Prevent caching of sensitive pages
+if (in_array($_GET['page'] ?? '', ['login', 'register', 'profile', 'security'])) {
+    header('Cache-Control: no-store, no-cache, must-revalidate, max-age=0');
+    header('Pragma: no-cache');
+    header('Expires: ' . gmdate('D, d M Y H:i:s', time() - 3600) . ' GMT');
+}

public_html/index.php

@@ -15,6 +15,9 @@
 // flush it later only when there is no redirect
 ob_start();
 
+// Apply security headers
+require_once '../app/includes/security_headers_middleware.php';
+
 // sanitize all input vars that may end up in URLs or forms
 require '../app/includes/sanitize.php';