保护您的 PHP 应用程序免受常见漏洞影响的基本安全实践

<?php
// insecure version
$user_id = $_get['id'];
$query = "select * from users where id = '$user_id'";
$result = mysqli_query($connection, $query);

// secure version
$user_id = $_get['id'];
$stmt = $connection->prepare("select * from users where id = ?");
$stmt->bind_param("i", $user_id);  // "i" for integer
$stmt->execute();
$result = $stmt->get_result();
?>

<?php
// insecure version
echo "<p>welcome, " . $_get['username'] . "</p>";

// secure version
echo "<p>welcome, " . htmlspecialchars($_get['username'], ent_quotes, 'utf-8') . "</p>";
?>

<?php
// generate csrf token
session_start();
if (empty($_session['csrf_token'])) {
    $_session['csrf_token'] = bin2hex(random_bytes(32));
}

// add token to form
echo '<form method="post" action="submit.php">';
echo '<input type="hidden" name="csrf_token" value="' . $_session['csrf_token'] . '">';
echo '<input type="text" name="data">';
echo '<input type="submit" value="submit">';
echo '</form>';
?>

<?php
session_start();
if ($_post['csrf_token'] !== $_session['csrf_token']) {
    die("csrf token validation failed.");
}

// process form data
$data = $_post['data'];
?>

<?php
session_start();

// regenerate session id to avoid fixation attacks
session_regenerate_id(true);

// configure secure session parameters
ini_set('session.cookie_httponly', 1); // prevent javascript access to session cookies
ini_set('session.cookie_secure', 1);   // ensure cookies are sent over https
ini_set('session.use_strict_mode', 1); // prevent accepting uninitialized session ids

// set session timeout
$_session['last_activity'] = time(); // update last activity time
if (time() - $_session['last_activity'] > 1800) { // 30 minutes timeout
    session_unset();
    session_destroy();
    session_start();
}
?>

<?php
$allowed_extensions = ['jpg', 'jpeg', 'png', 'gif'];
$file_name = $_files['file']['name'];
$file_extension = pathinfo($file_name, pathinfo_extension);

// check file extension
if (!in_array($file_extension, $allowed_extensions)) {
    die("invalid file type.");
}

// store in a safe location (outside web root) with a unique name
$target_dir = "/var/www/uploads/";
$target_file = $target_dir . basename($file_name);

if (move_uploaded_file($_files['file']['tmp_name'], $target_file)) {
    echo "file uploaded successfully.";
} else {
    echo "file upload failed.";
}
?>

header set content-security-policy "default-src 'self'; script-src 'self' 'unsafe-inline' https://trustedscripts.com"

<?php
// Validate integer input
$age = filter_input(INPUT_GET, 'age', FILTER_VALIDATE_INT);

if ($age === false) {
    die("Invalid age value.");
}

// Sanitize string input
$username = filter_input(INPUT_POST, 'username', FILTER_SANITIZE_STRING);
?>