File Inclusion (LFI/RFI)

Summary

File Inclusion attacks, including Local File Inclusion (LFI) and Remote File Inclusion (RFI), exploit vulnerabilities in web applications that improperly handle user-supplied input to include files. Attackers leverage these flaws to execute unauthorized code, disclose sensitive information, or compromise the target system by including malicious files from local or remote sources.

Key Characteristics

• Exploitation of insecure file inclusion functions in web applications.
• LFI targets files already present on the server, allowing attackers to read sensitive files or execute code.
• RFI involves including remote files, enabling attackers to execute arbitrary code hosted externally.
• Often facilitated by insufficient input validation and improper sanitization of user input.
• Can lead to remote code execution, data leakage, privilege escalation, and full system compromise.
• Commonly found in PHP-based applications but applicable to other languages with file inclusion features.

Defensive Controls

• Implement strict input validation and sanitization to prevent malicious input.
• Use allowlists for file paths and restrict file inclusion to trusted directories.
• Disable dynamic file inclusion where possible or use safer alternatives.
• Configure the web server and application to prevent execution of uploaded files.
• Keep software and libraries up to date to patch known vulnerabilities.
• Employ web application firewalls (WAFs) to detect and block suspicious file inclusion attempts.

Related Security Solutions

Web Application Firewalls (WAFs), secure coding practices, runtime application self-protection (RASP), vulnerability scanning tools, and intrusion detection/prevention systems (IDS/IPS) are commonly used to detect, prevent, and mitigate File Inclusion attacks.