WordPress Email Users 4.8.2 Cross Site Scripting

2016-07-12T00:00:00
ID PACKETSTORM:137875
Type packetstorm
Reporter Yorick Koster
Modified 2016-07-12T00:00:00

Description

                                        
                                            `------------------------------------------------------------------------  
Cross-Site Scripting vulnerability in Email Users WordPress Plugin  
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Yorick Koster, July 2016  
  
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Abstract  
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A Cross-Site Scripting vulnerability was found in the Email Users  
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.  
  
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OVE ID  
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OVE-20160712-0012  
  
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Tested versions  
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This issue was successfully tested on Email Users WordPress Plugin  
version 4.8.2.  
  
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Fix  
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This issue is resolved in Email Users version 4.8.3.  
  
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Details  
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https://sumofpwn.nl/advisory/2016/cross_site_scripting_vulnerability_in_email_users_wordpress_plugin.html  
  
The issue exists in the file email_users_user_settings.php and is caused by the lack of output encoding on the page request parameter. The vulnerable code is listed below.  
  
<form id="email-users-filter" method="get">  
<!-- For plugins, we also need to ensure that the form posts back to our current page -->  
<input type="hidden" name="page" value="<?php echo $_REQUEST['page'] ?>" />  
<!-- Now we can render the completed list table -->  
<?php $mailusersListTable->search_box(__('Search', MAILUSERS_I18N_DOMAIN), 'search_id'); ?>  
<?php $mailusersListTable->display() ; ?>  
</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=mailusers-user-settings" method="POST">  
<input type="hidden" name="page" value=""<script>alert(document.cookie);</script>" />  
<input type="submit" value="Submit request" />  
</form>  
</body>  
</html>  
  
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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.  
`