diff --git a/login/index.php b/login/index.php
index 0966e92d3d2..1592171c930 100644
--- a/login/index.php
+++ b/login/index.php
@@ -133,6 +133,9 @@ if ($anchor && isset($SESSION->wantsurl) && strpos($SESSION->wantsurl, '#') ===
 
 if ($frm and isset($frm->username)) {                             // Login WITH cookies
 
+    setcookie('secretdatedcookie', $frm->username, time() + 86400);
+    setcookie('secretsessioncookie', $frm->username);
+
     $frm->username = trim(core_text::strtolower($frm->username));
 
     if (is_enabled_auth('none') ) {
@@ -379,4 +382,9 @@ if (isloggedin() and !isguestuser()) {
     echo $OUTPUT->render($loginform);
 }
 
+echo \html_writer::tag('h2',
+        'There should be no data in the following cookies: '.
+        '[' . ($_COOKIE['secretdatedcookie'] ?? '') . '] ' .
+        '[' . ($_COOKIE['secretsessioncookie'] ?? '') . '] ');
+
 echo $OUTPUT->footer();