title: All Wordpress files are hacked. How to remove the encoded injection?
body: <p>A friend asked me to look up why his WordPress site is not working at all. It turned out it's hacked.</p>
  
  <p>At the beginning of all PHP files an encoded string is injected, something like this:</p>
  
  <pre><code>$zend_framework=" .... "; @error_reporting(0); $zend_framework("", "...
  </code></pre>
  
  <p>I have checked the version of WordPress at /wp-includes/version.php and it's  3.5.1.</p>
  
  <p>Have you ever experienced something like this? Do you know a solution of how can I fix these files?</p>