PHP files contain vulnerabilities and detailed explanation of prevention methods

Detailed explanation of PHP file inclusion vulnerabilities and prevention methods

In WEB applications, the file inclusion function is a very common function. However, file inclusion vulnerabilities can occur if user-entered parameters are not handled carefully. This vulnerability could allow an attacker to upload PHP code and include it into the application, thereby gaining control of the server. Therefore, it is very necessary to have an in-depth understanding of the causes and prevention methods of PHP file inclusion vulnerabilities.

Causes of PHP file inclusion vulnerabilities

The occurrence of PHP file inclusion vulnerabilities is usually related to the following two reasons:

1. Failure to properly filter user input data

In PHP, you can include one PHP file into another PHP file through functions such as include and require. If user-submitted data is used as the file path in these functions, the attacker can easily construct a PHP script containing malicious code and upload it to the server. For example:

<?php
   $page=$_GET['page'];
   include($page);
?>

In this example, the attacker can set the page parameter to http://example.com/shell.php to include the shell.php file into the application.

2. Failure to verify the validity of user input data

Even if user input data is filtered, attackers can still use other methods to achieve file inclusion vulnerabilities. For example, use relative paths such as ../ to access, or use

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