File Inclusion vulnerability allows an attacker to include a file, usually exploiting a "dynamic file inclusion" mechanisms implemented in the target application. The vulnerability occurs due to the use of user-supplied input without proper validation.

This can lead to something as outputting the contents of the file, but depending on the severity, it can also lead to:

• Code execution on the web server
• Code execution on the client-side such as JavaScript which can lead to other attacks such as cross site scripting (XSS)
• Denial of Service (DoS)
• Sensitive Information Disclosure

Remote file inclusion (RFI) is an attack targeting vulnerabilities in web applications that dynamically reference external scripts. The attacker aims to exploit the referencing function in an application to upload malware (e.g., backdoor shells) from a remote URL located within a different domain.

The consequences of a successful RFI attack include information theft, compromised servers and a site takeover that allows for content modification.