Verify that the post message source origin us https://tails.boum.org

wiki/src/install/inc/js/dave_2.js

@@ -3,7 +3,7 @@ document.addEventListener("DOMContentLoaded", function() {
   window.addEventListener("message", receiveMessage);
 
   function receiveMessage(event) {
-    if (event.source !== window || !event.data) {
+    if (event.source !== window || event.origin !== "https://tails.boum.org" || !event.data) {
       return;
     }
     if (event.data.action === "verifying") {