Hacked Wordpress index.php with refresh hook

index.php

<?php
$_start = microtime(TRUE);
$mem = new Memcache;
$mem->connect('127.0.0.1', 11211) or die('Memcache is dead');

$url = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
$key = md5($url);

$cache = !empty($_GET['refresh']) && $_GET['refresh'] == 'waku' ? FALSE : $mem->get($key);
if(!empty($cache['data'])) {
        $elapsed = microtime(TRUE) - $_start;
        $cache['data'] .= PHP_EOL . "<!-- Served from cache ".$elapsed." second -->";
        header('Content-Type: text/html');
        echo $cache['data']; exit;
}
else {
        ob_start("cb");
}

function cb($buffer) {
        $current_url = $_SERVER['HTTP_HOST'] . $_SERVER['REQUEST_URI'];
        $key = md5($current_url);
        $ttl = 60 * 60 * 24 * 30;

        $set = array(
                'data' => $buffer
        );

        global $mem;
        $mem->set($key, $set, false, $ttl);
    return $buffer;
}

/**
 * Front to the WordPress application. This file doesn't do anything, but loads
 * wp-blog-header.php which does and tells WordPress to load the theme.
 *
 * @package WordPress
 */

/**
 * Tells WordPress to load the WordPress theme and output it.
 *
 * @var bool
 */
define('WP_USE_THEMES', true);

/** Loads the WordPress Environment and Template */
require('./wp-blog-header.php');