How to ensure file system security?

Question

Information Security

How to ensure the security of the file system working on pure php + mysql? How do "coolhackers" upload their scripts to the server, download entire sites, etc.?

Answer 1

Usually using some kind of bug in the code. If it is possible to run arbitrary code on the system, then through this vulnerability, you can load a shell through which you can already access the server and all other files.
www.sitepoint.com/top-10-php-security-vulnerabilities