400 new phishing sites have been identified recently and those share a common origin in terms of how those are being hidden on webservers without their admins knowing. I have quoted the important points below in what you need to look for especially if you are using Let's Encrypt HTTPS. However this further points out that these servers are not properly secured in the first place, so get your ducks in line guys! One of the most common legitimate uses of the /.well-known/ directory is to prove control over a domain. When a secure website uses the Automatic Certificate Management Environment (ACME) protocol to manage its SSL certificate, the issuer will verify ownership by checking for a unique token in /.well-known/acme-challenge/ or /.well-known/pki-validation/. Consequently, most of the phishing attacks that make use of the /.well-known/ directory have been deployed on sites that support HTTPS, using certificates issued by ACME-driven certificate authorities like Let's Encrypt and cPanel. Due to the success of Let's Encrypt and ACME, millions of websites now have a /.well-known/ directory in their web root, although many website administrators may be oblivious to its presence – particularly if they did not create the directory themselves. The directory can also easily be overlooked, as a bare ls command will treat files or directories that start with a "." as hidden. These factors make /.well-known/ an ideal place to smuggle phish onto a compromised web server.