Do not allow referrer to modify the sender

http://mathiasbynens.github.io/rel-noopener/

website/source/downloads.html.erb

@@ -25,8 +25,8 @@ description: |-
         <a href="https://releases.hashicorp.com/consul/<%= latest_version %>/consul_<%= latest_version %>_SHA256SUMS.sig">
           verify the checksums signature file
         </a>
-        which has been signed using <a href="https://www.hashicorp.com/security.html" target="_TOP">HashiCorp's GPG key</a>.
+        which has been signed using <a href="https://www.hashicorp.com/security.html" target="_blank" rel="nofollow noopener noreferrer">HashiCorp's GPG key</a>.
-        You can also <a href="https://releases.hashicorp.com/consul/" target="_TOP">download older versions of Consul</a> from the releases service.
+        You can also <a href="https://releases.hashicorp.com/consul/" target="_blank" rel="nofollow noopener noreferrer">download older versions of Consul</a> from the releases service.
       </p>
     </div>
   </div>
@@ -59,7 +59,7 @@ description: |-
 
   <div class="row">
     <div class="col-md-12 poweredby">
-      <a href="https://www.fastly.com?utm_source=hashicorp" target="_TOP">
+      <a href="https://www.fastly.com?utm_source=hashicorp" target="_blank" rel="nofollow noopener noreferrer">
         <%= image_tag "fastly_logo.png" %>
       </a>
     </div>