It is the Distributed Version of Thug, by which all systems across the world running thug will get connect. Then URLs will be distributed among them to process and get back the results to the main server.
I don't know if ThugD is still maintained but I wanted to let you know that the download files for ThugD have gotten onto some list Google maintains of harmful files.
I received this alert in Read the Docs' Google Search Console which is how Google gives feedback to webmasters.