Secure File Uploads with GitHub Copilot

<?php
if (isset($_FILES['uploaded_file'])) {
    $target_path = "uploads/";
    $target_path = $target_path . basename($_FILES['uploaded_file']['name']);

    if(move_uploaded_file($_FILES['uploaded_file']['tmp_name'], $target_path)) {
        echo "The file ". basename($_FILES['uploaded_file']['name']). " has been uploaded.";
    } else{
        echo 

The file upload feature in the provided PHP script has several security vulnerabilities:

1. **Unrestricted File Types**: The script does not validate the type of the file being uploaded. Malicious users could upload a PHP script or other executable files, leading to server compromise.

2. **Insecure File Names**: Using `basename($_FILES['uploaded_file']['name'])` directly without sanitization allows for potential directory traversal attacks and can lead to overwriting important files.

3. **Lack of Size Validation**: There's no check on the size of the uploaded file, making the server vulnerable to denial-of-service (DoS) attacks through resource exhaustion.

4. **No Antivirus Scanning**: Uploaded files are not scanned for malware, which could result in uploading and storing malicious files on the server.

5. **Insecure Storage**: Files are stored directly in an accessible directory without any form of obfuscation or protection, posing a risk if sensitive files are uploaded.

To improve the security of the file upload feature, consider implementing the following measures:

```php
<?php
if (isset($_FILES['uploaded_file'])) {
    $target_directory = "uploads/";
    $safe_filename = preg_replace('/[^a-zA-Z0-9-_\.]/','', basename($_FILES['uploaded_file']['name']));
    $target_path = $target_directory . $safe_filename;

    // Validate file size and type
    $allowed_file_types = ['jpg', 'png', 'pdf'];
    $max_file_size = 5000000; // 5MB
    $file_type = strtolower(pathinfo($safe_filename, PATHINFO_EXTENSION));

    if (!in_array($file_type, $allowed_file_types)) {
        die("Error: Only JPG, PNG, and PDF files are allowed.");
    }

    if ($_FILES['uploaded_file']['size'] > $max_file_size) {
        die("Error: File size exceeds the maximum allowed limit.");
    }

    // Move the file to the target path
    if (move_uploaded_file($_FILES['uploaded_file']['tmp_name'], $target_path)) {
        echo "The file ". $safe_filename . " has been uploaded safely.";
    } else {
        echo "There was an error uploading the file, please try again!";
    }
}
?>