Local File Inclusion (LFI)
A vulnerability allowing attackers to execute files on a server via manipulated input.
Understanding Local File Inclusion (LFI)
LFI occurs when a web application dynamically includes files without properly validating user input. Attackers manipulate file paths to access sensitive files, such as configuration files, source code, and system logs.
How Local File Inclusion Works
Vulnerable File Inclusion Function
Web applications often use
include(),require(), or similar functions to dynamically load files.If user input is not sanitized, an attacker can modify the file path.
Manipulating File Paths
Attackers use directory traversal techniques (
../../etc/passwd) to access system files.
Example vulnerable PHP code:
<?php
include($_GET['file']);
?>
If accessed via
http://example.com/index.php?file=../../etc/passwd, it may display system user credentials.
Executing Malicious Code
If an attacker uploads a PHP shell and includes it via LFI, remote code execution can occur.
Example: Injecting logs with PHP code and including the log file for execution.
Challenges and Considerations
Balancing Security & Functionality: Strict security measures may impact dynamic file inclusion features.
Zero-Day Vulnerabilities: New LFI techniques continue to emerge, requiring continuous monitoring.
User Awareness & Training: Developers must be educated on secure coding practices to prevent LFI.
Local File Inclusion (LFI) remains a critical web security issue, requiring proactive defense mechanisms to prevent sensitive data exposure and system compromise.