fpoller

<p>Gives the following options for making the WordPress installation more private:</p>
<ul>
<li>Protect content from being viewed to users who hasn’t logged in</li>
<li>Disable all feeds</li>
<li>Only serve uploaded files to logged in users</li>
<li>IP address based exceptions for the above options</li>
</ul>


Private WP suite

Adds option in the admin panel for making your blog (including rss feeds and uploaded files) private.

Yslo

<p>Empty spaces and special characters can create some problems.</p>
<h4>Features</h4>
<ul>
<li>Improved default function <a href="https://codex.wordpress.org/Function_Reference/sanitize_file_name" rel="nofollow ugc">sanitize_file_name()</a></li>
<li>Remove latin special characters used in file name</li>
<li>Make file name lowercase</li>
</ul>


WP Sanitize File Name Plus

Sanitize file names and enhance security.

Private WP suite vs WP Sanitize File Name Plus