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/**
* TfishSession class file.
*
* @copyright Simon Wilkinson 2013-2017 (https://tuskfish.biz)
* @license https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
* @author Simon Wilkinson <[email protected]>
* @version Release: 1.0
* @since 1.0
* @package security
*/
// Enable strict type declaration.
declare(strict_types=1);
if (!defined("TFISH_ROOT_PATH")) die("TFISH_ERROR_ROOT_PATH_NOT_DEFINED");
/**
* Tuskfish session security class.
*
* Provides functions for managing sessions in a security-conscious manner.
*
* @copyright Simon Wilkinson 2013-2017 (https://tuskfish.biz)
* @license https://www.gnu.org/licenses/old-licenses/gpl-2.0.en.html GNU General Public License (GPL) V2
* @author Simon Wilkinson <[email protected]>
* @version Release: 1.0
* @since 1.0
* @package security
*/
class TfishSession
{
/** No instantiation permitted. */
final private function __construct()
{
}
/** No cloning permitted */
final private function __clone()
{
}
/**
* Unset session variables and destroy the session.
*/
public static function destroy()
{
$_SESSION = [];
session_destroy();
session_start();
self::setToken();
}
/**
* Shorthand admin privileges check.
*
* For added security this could retrieve an encrypted token, preferably the SSL session id,
* although thats availability seems to depend on server configuration.
*
* @return bool True if admin false if not.
*/
public static function isAdmin()
{
if (isset($_SESSION['TFISH_LOGIN']) && $_SESSION['TFISH_LOGIN'] === true) {
return true;
} else {
return false;
}
}
/**
* Checks if a session has expired and sets last seen activity flag.
*
* @param object $tfish_preference TfishPreference object.
* @return bool True if session has expired, false if not.
*/
public static function isExpired(TfishPreference $tfish_preference)
{
// Check if session carries a destroyed flag and kill it if the grace timer has expired.
if (isset($_SESSION['destroyed']) && time() > $_SESSION['destroyed']) {
return true;
}
// Check for "last seen" timestamp.
$last_seen = isset($_SESSION['last_seen']) ? (int) $_SESSION['last_seen'] : false;
// Check expiry (but not if session_life === 0).
if ($last_seen && $tfish_preference->session_life > 0) {
if ($last_seen && (time() - $last_seen) > ($tfish_preference->session_life * 60)) {
return true;
}
}
// Session not seen before, add an activity timestamp.
$_SESSION['last_seen'] = time();
return false;
}
/**
* Checks if client IP address or user agent has changed.
*
* These tests can indicate session hijacking but are by no means definitive; however they do
* indicate elevated risk and the session should be regenerated as a counter measure.
*
* @return bool True if IP/user agent are unchanged, false otherwise.
*/
public static function isClean()
{
$browser_profile = '';
if (isset($_SERVER['REMOTE_ADDR'])) {
$browser_profile .= $_SERVER['REMOTE_ADDR'];
}
if (isset($_SERVER['HTTP_USER_AGENT'])) {
$browser_profile .= $_SERVER['HTTP_USER_AGENT'];
}
$browser_profile = hash('sha256', $browser_profile);
if (isset($_SESSION['browser_profile'])) {
return $_SESSION['browser_profile'] === $browser_profile;
}
$_SESSION['browser_profile'] = $browser_profile;
return true;
}
/**
* Authenticate the user and establish a session.
*
* The number of failed login attempts is tracked. Subsequent login attempts will sleep for
* an equivalent number of seconds before processing, in order to frustrate brute force attacks.
* A successful login will reset the counter to zero. Note that the password field is
* unrestricted content.
*
* @param string $email Input email.
* @param string $password Input password.
*/
public static function login(string $email, string $password)
{
// Check email and password have been supplied
if (empty($email) || empty($password)) {
// Issue incomplete form warning and redirect to the login page.
self::logout(TFISH_ADMIN_URL . "login.php");
} else {
// Validate the admin email (which functions as the username in Tuskfish CMS)
$clean_email = TfishFilter::trimString($email);
if (TfishFilter::isEmail($clean_email)) {
self::_login($clean_email, $password);
} else {
// Issue warning - email should follow email format
self::logout(TFISH_ADMIN_URL . "login.php");
}
}
}
/** @internal */
private static function _login(string $clean_email, string $dirty_password)
{
// Query the database for a matching user.
$statement = TfishDatabase::preparedStatement("SELECT * FROM user WHERE "
. "`admin_email` = :clean_email");
$statement->bindParam(':clean_email', $clean_email, PDO::PARAM_STR);
$statement->execute();
$user = $statement->fetch(PDO::FETCH_ASSOC);
// Authenticate user by calculating their password hash and comparing it to the one on file.
if ($user) {
// If the user has previous failed login atttempts sleep to frustrate brute force attacks.
if ($user['login_errors']) {
sleep((int) $user['login_errors']);
}
$password_hash = TfishSecurityUtility::recursivelyHashPassword($dirty_password, 100000,
TFISH_SITE_SALT, $user['user_salt']);
// If login successful regenerate session due to privilege escalation.
if ($password_hash === $user['password_hash']) {
self::regenerate();
$_SESSION['TFISH_LOGIN'] = true;
$_SESSION['user_id'] = (int) $user['id'];
// Reset failed login counter to zero.
TfishDatabase::update('user', (int) $user['id'], array('login_errors' => 0));
// Redirect to admin page.
header('location: ' . TFISH_ADMIN_URL . "admin.php");
exit;
} else {
// Increment failed login counter, destroy session and redirect to the login page.
TfishDatabase::updateCounter((int) $user['id'], 'user', 'login_errors');
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
} else {
// Redirect to login page.
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
}
/**
* Authenticate the user with two factors and establish a session.
*
* Requires a Yubikey hardware token as the second factor. Note that the authenticator type
* is not declared, as the desired response is to logout and redirect, rather than to throw
* an error.
*
* @param string $dirty_password Input password.
* @param string $dirty_otp Input Yubikey one-time password.
* @param object $yubikey Instance of the TfishYubikeyAuthenticator class.
*/
public static function twoFactorLogin(string $dirty_password, string $dirty_otp, $yubikey)
{
// Check password, OTP and Yubikey have been supplied
if (empty($dirty_password) || empty($dirty_otp) || empty($yubikey)) {
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
$dirty_otp = TfishFilter::trimString($dirty_otp);
// Yubikey OTP should be 44 characters long.
if (mb_strlen($dirty_otp, "UTF-8") != 44) {
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
// Yubikey OTP should be alphabetic characters only.
if (!TfishFilter::isAlpha($dirty_otp)) {
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
// Yubikey should be TfishYubikeyAuthenticator class.
if (!is_object($yubikey) || get_class($yubikey) != 'TfishYubikeyAuthenticator') {
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
// Public ID is the first 12 characters of the OTP.
$dirty_id = mb_substr($dirty_otp, 0, 12, 'UTF-8');
self::_twoFactorLogin($dirty_id, $dirty_password, $dirty_otp, $yubikey);
}
/** @internal */
private static function _twoFactorLogin(string $dirty_id, string $dirty_password, string $dirty_otp,
TfishYubikeyAuthenticator $yubikey)
{
$user = false;
$first_factor = false;
$second_factor = false;
// Query the database for a matching user.
$statement = TfishDatabase::preparedStatement("SELECT * FROM user WHERE "
. "`yubikey_id` = :yubikey_id OR "
. "`yubikey_id2` = :yubikey_id");
$statement->bindParam(':yubikey_id', $dirty_id, PDO::PARAM_STR);
$statement->execute();
$user = $statement->fetch(PDO::FETCH_ASSOC);
if (empty($user)) {
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
// First factor authentication: Calculate password hash and compare to the one on file.
$password_hash = TfishSecurityUtility::recursivelyHashPassword($dirty_password, 100000,
TFISH_SITE_SALT, $user['user_salt']);
if ($password_hash === $user['password_hash']) {
$first_factor = true;
}
// Second factor authentication: Submit one-time password to Yubico authentication server.
$second_factor = $yubikey->verify($dirty_otp);
// If both checks are good regenerate session due to priviledge escalation and login.
if ($first_factor === true && $second_factor === true) {
self::regenerate();
$_SESSION['TFISH_LOGIN'] = true;
// Added as a handle for the password change script.
$_SESSION['user_id'] = (int) $user['id'];
header('location: ' . TFISH_ADMIN_URL . "admin.php");
exit;
}
// Otherwise force logout.
self::logout(TFISH_ADMIN_URL . "login.php");
exit;
}
/**
* Returns a login or logout link for insertion in the template.
*
* @return string HTML login or logout link.
*/
public static function loginLink()
{
if (self::isAdmin()) {
return '<a href="' . TFISH_ADMIN_URL . 'login.php?op=logout">' . TFISH_LOGOUT . '</a>';
} else {
return '<a href="' . TFISH_ADMIN_URL . 'login.php">' . TFISH_LOGIN . '</a>';
}
}
/**
* Destroys the current session on logout
*
* @param string $url_redirect The URL to redirect the user to on logging out.
*/
public static function logout(string $url_redirect = '')
{
$clean_url = '';
if (!empty($url_redirect)) {
$clean_url = TfishFilter::isUrl($url_redirect) ? $url_redirect : '';
}
self::_logout($clean_url);
}
/** @internal */
private static function _logout(string $clean_url)
{
// Unset all of the session variables.
$_SESSION = [];
// Destroy the session cookie, DESTROY IT ISILDUR!
if (ini_get("session.use_cookies")) {
$params = session_get_cookie_params();
setcookie(session_name(), '', time() - 42000, $params["path"], $params["domain"],
$params["secure"], $params["httponly"]);
}
// Destroy the session and redirect
session_destroy();
if ($clean_url) {
header('location: ' . $clean_url);
exit;
} else {
header('location: ' . TFISH_URL);
exit;
}
}
/**
* Reset session data after a session hijacking check fails. This will force logout.
*/
public static function reset()
{
$_SESSION = [];
$browser_profile = '';
if (isset($_SERVER['REMOTE_ADDR'])) {
$browser_profile .= $_SERVER['REMOTE_ADDR'];
}
if (isset($_SERVER['HTTP_USER_AGENT'])) {
$browser_profile .= $_SERVER['HTTP_USER_AGENT'];
}
$_SESSION['browser_profile'] = hash('sha256', $browser_profile);
}
/**
* Regenerates the session ID.
*
* Called whenever there is a privilege escalation (login) or at random intervals to reduce
* risk of session hijacking. Note that the cross-site request forgery validation token remains
* the same, unless the session is destroyed. This is to prevent the random session ID
* regeneration events creating false positive CSRF checks.
*
* Note that it allows the new and old sessions to co-exist for a short period, this is to
* avoid headaches with flaky network connections and asynchronous (AJAX) requests, as explained
* in the PHP Manual warning: http://php.net/manual/en/function.session-regenerate-id.php
*/
public static function regenerate()
{
// If destroyed flag is set, no need to regenerate ID as it has already been done.
if (isset($_SESSION['destroyed'])) {
return;
}
// Flag old session for destruction in (arbitrary) 10 seconds.
$_SESSION['destroyed'] = time() + 10;
// Create new session. Update ID and keep current session info. Old one is not destroyed.
session_regenerate_id(false);
// Get the (new) session ID.
$new_session_id = session_id();
// Lock the session and close it.
session_write_close();
// Set the session ID to the new value.
session_id($new_session_id);
// Now working with the new session. Note that old one still exists and both carry a
// 'destroyed' flag.
session_start();
// Set a cross-site request forgery token.
self::setToken();
// Remove the destroyed flag from the new session. Old one will be destroyed next time
// isExpired() is called on it.
unset($_SESSION['destroyed']);
}
/**
* Sets a token for use in cross-site request forgery checks on form submissions.
*
* A random token is generated and stored in the current session (if not already set). The value
* of this token is included as a hidden field in forms when they are loaded by the user. This
* allows forms to be validated via validateFormToken().
*/
public static function setToken()
{
if (empty($_SESSION['token'])) {
$_SESSION['token'] = bin2hex(random_bytes(32)) ;
}
}
/**
* Initialises a session and sets session cookie parameters to security-conscious values.
*
* @param object $tfish_preference TfishPreference object.
*/
public static function start(TfishPreference $tfish_preference)
{
// Force session to use cookies to prevent the session ID being passed in the URL.
ini_set('session.use_cookies', '1');
ini_set('session.use_only_cookies', '1');
// Session name. If the preference has been messed up it will assign one.
$session_name = isset($tfish_preference->session_name)
? $tfish_preference->session_name : 'tfish';
// Session life time, in seconds. '0' means until the browser is closed.
$lifetime = $tfish_preference->session_lifetime;
// Path on the domain where the cookie will work. Use a single slash for all paths (default,
// as there are admin checks in some templates).
$path = '/';
// Cookie domain, for example www.php.net. To make cookies visible on all subdomains
// (default) prefix with dot eg. '.php.net'
$domain = isset($domain) ? $domain : ltrim($_SERVER['SERVER_NAME'], 'www');
// If true the cookie will only be sent over secure connections.
$secure = isset($_SERVER['HTTPS']);
// If true PHP will *attempt* to send the httponly flag when setting the session cookie.
$http_only = true;
// Set the parameters and start the session.
session_name($session_name);
session_set_cookie_params($lifetime, $path, $domain, $secure, $http_only);
session_start();
// Set a CSRF token.
self::setToken();
// Check if the session has expired.
if (self::isExpired($tfish_preference))
self::destroy();
// Check for signs of session hijacking and regenerate if at risk. 10% chance of doing it
// anyway.
if (!self::isClean()) {
self::reset();
self::regenerate();
} elseif (rand(1, 100) <= 10) {
self::regenerate();
}
}
/**
* Validate a cross-site request forgery token from a form submission.
*
* Forms contain a hidden field with a random token taken from the user's session. This token
* is used to validate that a form submission did indeed originate from the user, by comparing
* the value against that stored in the user's session. If they do not match then the request
* could be a forgery and the form submission should be rejected.
*
* @param string $token A form token to validate against the user's session.
* @return boolean True if token is valid, otherwise false.
*/
public static function validateToken(string $token)
{
$clean_token = TfishFilter::trimString($token);
// Valid token.
if (!empty($_SESSION['token']) && $_SESSION['token'] === $clean_token) {
return true;
}
// Invalid token - redirect to warning message and cease processing the request.
header('location: ' . TFISH_URL . 'token.php');
exit;
}
}