    public function isAuthorizedBackendUserSession()
    {
        if (!$this->hasSessionCookie()) {
            return false;
        }
        $this->initializeSession();
        if (empty($_SESSION['authorized']) || empty($_SESSION['isBackendSession'])) {
            return false;
        }
        return !$this->isExpired();
    }
According to WASC, "Insufficient Session Expiration is when a web site permits an attacker to reuse old session credentials or session IDs for authorization."