Ayesh Karunaratne

WordPress has a 12-year-old unfixed security vulnerability that it does not properly validate incoming comments.
An attacker can trick both anonymous and logged-in users to post comments on a victim site without them realizing, while using their own credentials.
See this issue for more information: https://core.trac.wordpress.org/ticket/10931
This is a tiny (fewer than 40 effect lines of code) module that adds a secure token to the comment form and validate it before accepting any comment, thus making your comment forms secure as they should\’ve been for all these years!
It provides no UI – just install it, and you are all set!
<ol>
<li>This plugin adds a secret cryptographically-secure token to the comment form. This is a unique value and is computationally impractical to guess it.</li>
<li>Upon comment submission, the comment is rejected if the secret tokens are not present or computationally invalid.</li>
</ol>

Comment Form CSRF Protection

Prevent Cross-Site Request Forgery attacks on your comments form.

StampyCode

This plugin addresses the need for a simple way to add HTTP headers to outbound HTTP responses in your site.
These headers can include custom ones specific to your application, or can be security related. Some you may wish to specify to protect your site may include:
<ul>
<li>Public-Key-Pins</li>
<li>Strict-Transport-Security</li>
<li>X-Frame-Options</li>
<li>X-XSS-Protection</li>
<li>X-Content-Type-Options</li>
<li>Content-Security-Policy</li>
<li>Content-Security-Policy-Report-Only</li>
</ul>
<h3>Related Links</h3>
<ul>
<li><a href="http://www.troyhunt.com/2015/09/introducing-you-to-browser-security.html" rel="nofollow ugc">Troy Hunt – Introducing you to browser security headers on Pluralsight</a></li>
<li><a href="https://app.pluralsight.com/library/courses/browser-security-headers" rel="nofollow ugc">PluralSight.com – Introduction to Browser Security Headers</a></li>
<li><a href="https://www.owasp.org/index.php/List_of_useful_HTTP_headers" rel="nofollow ugc">OWASP – List of useful HTTP headers</a></li>
<li><a href="https://scotthelme.co.uk/hardening-your-http-response-headers/" rel="nofollow ugc">Scott Helme – Hardening your HTTP response headers</a></li>
</ul>

Headit

Headit is a simple plugin to allow you to add custom HTTP response headers to your site.

Comment Form CSRF Protection vs Headit