The Magento Connect Manager is not working. Is this by design? or is it a bug?

The /downloader/ path is shown as: Not Found 404

There is a another way to root the box. You don’t want the Magento Connect Manager…

It was removed because only one person could exploit at a time with that method. The working method is well documented and not too hard to find

Read the thread again. You will be able to find the name of method.
Hack The Box