Electro Sales Corporation / Electro Systems
While the story explores the accidental discovery of these files, modern tools are designed to prevent such "parent directory" leaks. Creating Private Spaces
However, if the server is missing that default file and directory listing is left turned on, the server won't show an error page. Instead, it will display a raw, text-and-link list of every single file and folder stored inside that directory. This is called a "Directory Listing" or an "Index."
Malicious actors use automated scripts to download entire "Parent Directories" to harvest data for identity theft or to re-host the images on "leaked" content sites.