How can formats be checked, protocols excluded, and existence verified to mitigate security risks when including PHP files using $_GET parameters?

To mitigate security risks when including PHP files using $_GET parameters, formats can be checked by verifying that the file name contains only alphanumeric characters and periods, protocols can be excluded by ensuring that the file path does not contain "http://" or "https://", and existence can be verified by checking if the file exists before including it. 

if(isset($_GET['file']) && preg_match('/^[a-zA-Z0-9.]+$/', $_GET['file']) && strpos($_GET['file'], 'http://') === false && strpos($_GET['file'], 'https://') === false && file_exists($_GET['file'])) {
    include($_GET['file']);
} else {
    // Handle invalid file parameter
}

Keywords

PHP $_GET parameters file inclusion security risks validation

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