But plenty of administrators make mistakes in setting them up, sometimes leading to the server's real IP address being leaked, or they might leave identifying metadata in files uploaded to the site.

Now, a researcher has developed a custom tool for automatically scanning Tor hidden services for a slew of vulnerabilities and issues, meaning anyone, from dark web drug lords to people hosting whistleblowing platforms, can make sure that their site really is protected.

"I want anonymity tools to be the best; there are people whose lives depend on them," Sarah Jamie Lewis, the independent security researcher who came up with the tool, told Motherboard in an encrypted chat.