In many legacy or simple web setups, auth_user_file.txt serves as a flat-file database containing usernames and password hashes. Its exposure typically occurs when an administrator mistakenly places the file within the web server's rather than in a protected, non-public directory.
: If users reuse passwords across different platforms, a breach here could compromise more sensitive accounts, such as work email or social media. Why Storing Credentials in Plain Text is Dangerous
: Attackers can easily retrieve the list of usernames and their corresponding password hashes.
To prevent sensitive files like auth_user_file.txt from appearing in search results, web administrators should implement several layers of protection: Google for Developers Block Search Indexing with noindex - Google for Developers