WordPress Simple Membership 3.2.8 Cross Site Scripting
Posted on 14 July 2016
------------------------------------------------------------------------ Cross-Site Scripting vulnerability in Simple Membership WordPress Plugin ------------------------------------------------------------------------ Yorick Koster, July 2016 ------------------------------------------------------------------------ Abstract ------------------------------------------------------------------------ A Cross-Site Scripting vulnerability was found in the Simple Membership 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-20160712-0016 ------------------------------------------------------------------------ Tested versions ------------------------------------------------------------------------ This issue was successfully tested on Simple Membership WordPress Plugin version 3.2.8. ------------------------------------------------------------------------ Fix ------------------------------------------------------------------------ This issue is resolved in Simple Membership version 3.2.9. ------------------------------------------------------------------------ Details ------------------------------------------------------------------------ https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_simple_membership_wordpress_plugin.html The issue exists in several PHP files and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below. class.swpm-members.php: 'edit' => sprintf('<a href="admin.php?page=%s&member_action=edit&member_id=%s">Edit</a>', $_REQUEST['page'], $item['member_id']), [...] onclick="return confirm('Are you sure you want to delete this entry?')">Delete</a>', $_REQUEST['page'], $item['member_id']), class.swpm-membership-levels.php: 'edit' => sprintf('<a href="admin.php?page=%s&level_action=edit&id=%s">Edit</a>', $_REQUEST['page'], $item['id']), [...] onclick="return confirm('Are you sure you want to delete this entry?')">Delete</a>', $_REQUEST['page'], $item['id']), admin_members_list.php: <input type="hidden" name="page" value="<?php echo $_REQUEST['page']; ?>" /> admin_all_payment_transactions.php: <input type="hidden" name="page" value="<?php echo $_REQUEST['page']; ?>" /> 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=simple_wp_membership" 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.
