# Security\_helper

This Helper defines several **security functions** to sanitize user input and prevent security vulnerabilities such as **XSS (Cross-Site Scripting), SQL Injection, and Directory Traversal attacks**.

## Prevent XSS

* Converts special characters into HTML entities (e.g., `<` becomes `&lt;`, `>` becomes `&gt;`).
* Prevents malicious JavaScript from being injected into web pages.

```php
function xss_clean($data) {
    return htmlspecialchars($data, ENT_QUOTES, 'UTF-8');
}
```

Example:

```php
$user_input = "<script>alert('Hacked!');</script>";
$clean_input = xss_clean($user_input);
echo $clean_input; 
// Output: &lt;script&gt;alert('Hacked!');&lt;/script&gt;
```

## Clean Input Data to Prevent Attacks

* **Removes unnecessary spaces and backslashes**.
* **Strips out single (`'`) and double (`"`) quotes** to prevent SQL Injection.
* **Removes any special characters except letters, numbers, spaces, and punctuation**.

**Example:**

```php
$user_input = " DROP TABLE users; ";
$cleaned_input = clean_input($user_input);
echo $cleaned_input; 
// Output: DROP TABLE users
```

**Security Benefit:** Protects against **SQL Injection and XSS attacks**.

## Secure&#x20;

These functions **sanitize user input from URL parameters (`$_GET`) and form data (`$_POST`)**.

```php
// Get data from URL parameters
function S_GET($key, $default = null) {
    if (isset($_GET[$key])) {
        return clean_input($_GET[$key]);
    }
    return $default;
}

// Get data from form
function S_POST($key, $default = null) {
    if (isset($_POST[$key])) {
        return clean_input($_POST[$key]);
    }
    return $default;
}

// Get data from $_GET and $_POST
function S_REQUEST($key, $default = null) {
    if (isset($_REQUEST[$key])) {
        return clean_input($_REQUEST[$key]);
    }
    return $default;
}

// Check data from $_GET is exist
function HAS_GET($key) {
    return isset($_GET[$key]);
}

// Check data from $_POST is exist
function HAS_POST($key) {
    return isset($_POST[$key]);
}

// Check data from both $_GET and $_POST
function HAS_REQUEST($key) {
    if (isset($_REQUEST[$key])) {
        return true;
    }
    return false;
}
```

Example:

```php
$btn    = S_POST('submit', 'default_value');
$id     = S_GET('id', 'default_value');

if (HAS_GET('id')) {
    echo "ID exists in the URL";
}

if (HAS_POST('submit')) {
    echo "Form submitted";
}
```

### Secure URIs to Prevent Attacks

* **Removes dangerous characters** from URLs.
* **Prevents directory traversal attacks** by stripping out `..` and `...`.
* **Allows only alphanumeric characters, underscores (`_`), hyphens (`-`), and dots (`.`) in URL segments**.

Example using `uri_security()`:

```php
$unsafe_uri = "/admin/../../config.php";
$safe_uri = uri_security($unsafe_uri);
echo $safe_uri; 
// Output: admin/config.php
```

**Security Benefit:** Prevents **unauthorized file access and path traversal attacks**.

### Secure All `$_GET` Parameters

* **Sanitizes all `$_GET` keys and values**.
* **Removes dangerous characters** while keeping alphanumeric characters, underscores (`_`), and dashes (`-`).
* **Prevents GET parameter manipulation attacks.**

Example using `sget_security()`**:**

<pre class="language-php"><code class="lang-php"><strong>$_GET['&#x3C;script>alert(1)&#x3C;/script>'] = '123';
</strong>sget_security();
print_r($_GET);

// Output: Array([scriptalert1script] => 123)
</code></pre>

**Security Benefit:** Prevents **parameter-based attacks**.

## Security\_helper in Controller

```php
<?php
namespace App\Controllers;

use System\Core\BaseController;
use App\Models\UsersModel;

class UsersController extends BaseController {
    protected $usersModel;

    public function __construct() {
        $this->usersModel = new UsersModel();
    }
    
    public function profile(){
        $id = S_GET('id') ?? ''; 
        if(empty($id)) {
            $userInfo = $this->usersModel->getUserById($id);
        }
    }
    
    public function login() {
        if (HAS_POST('username')){
            $csrf_token = S_POST('csrf_token') ?? '';
            
            $input = [
                'username'  =>  S_POST('username') ?? '',
                'password'  =>  S_POST('password') ?? ''
            ];
            
            // Validate data $input
            
            $this->render('auth', 'Backend/Auth/login');
    }
}
```

{% hint style="success" %}
Conclusion

These functions improve security by preventing **XSS**, **SQL Injection**, and **Path Traversal attacks**
{% endhint %}