    protected function _log($message, $backtrace = null) {
        if (!$this->_debug)
            return true;

        $data = sprintf("[%s] %s\n", date('r'), $message);
        if ($backtrace) {
            $debug = print_r($backtrace, true);
            $data .= $debug . "\n";
        }
        $data = strtr($data, '<>', '..');
        
        $filename = w3_debug_log('sns');

        return @file_put_contents($filename, $data, FILE_APPEND);
    }
The web application does not, or can not, sufficiently verify whether a well-formed, valid, consistent request was intentionally provided by the user who submitted the request.