Are these hackers?

[Amaury]

If you want to fix the unknown location, you can create a plugin.

Title: Index.php - Unknown Location
Content:

if (strpos($userinfo['location'], 'index.php') !== false) 
{
  $userinfo['action'] = 'Viewing Index';
$userinfo['where'] = '<a href="index.php'.$vbulletin->session->vars[sessionurl].'">[Forum Name] Forum</a>';
  $handled = true;
}

The title can be whatever, of course.