: Automating the decompression on the server using libraries like RarArchive in PHP.

: Creating an HTML restricted to the .rar extension.

Are you referring to a (like Hack The Box) or a particular file you found on your system?

If you are investigating a suspicious file or activity named uploadxyzrar , write-ups typically detail the :

: The site might only allow images but can be tricked into accepting a .rar file that contains a PHP shell.

: Using PHP or Python to check the MIME type and extension to prevent malicious uploads.