What potential security risks are involved in including files based on user input in PHP scripts?

Including files based on user input in PHP scripts can lead to security risks such as remote code execution, directory traversal attacks, and file inclusion vulnerabilities. To mitigate these risks, it is important to validate and sanitize user input before using it to include files in PHP scripts. One way to do this is to restrict the allowed files to a predefined list or use whitelisting to ensure that only specific files can be included. 

$user_input = $_GET['file'];

$allowed_files = ['file1.php', 'file2.php', 'file3.php'];

if (in_array($user_input, $allowed_files)) {
    include($user_input);
} else {
    echo "Invalid file.";
}

Keywords

directory traversal remote code execution file inclusion vulnerability input validation PHP include function

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