In technical terms, an "index of" page is a server-generated list of files within a directory. When a web server doesn't have an "index.php" or "index.html" file to display a polished webpage, it simply lists everything in that folder. Movie enthusiasts use Google Dorks (specialized search strings) like intitle:"index of" Tiger Zinda Hai to find these unprotected directories and download the movie files directly without clicking through ads. About the Movie: Tiger Zinda Hai (2017)
Files in open directories are unvetted. What looks like a .mp4 file could be an executable script that installs malware on your device.