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Insecure service configuration - Request Validation

Need​

Secure service configuration - Request Validation

Context​

  • Usage of PHP 7.0 for server-side scripting and web development
  • Usage of Request for making HTTP requests in Node.js
  • Usage of Auth for user authentication and authorization

Description​

Non compliant code​

Route::post('/user/update', function (Request $request) {
    $user = Auth::user();
    $user->name = $request->input('name');
    $user->email = $request->input('email');
    $user->save();
    return redirect('/user/profile');
});

In the above code snippet, the POST route /user/update is defined to update the current logged-in user's name and email. This route does not have any validation checks in place for the incoming request data.

The user's name and email are directly taken from the request input and saved to the database. This means whatever data comes in the request is directly saved to the database, without any sanitization or validation.

This is a serious security vulnerability as it opens up the system to cross-site scripting (XSS) attacks. An attacker can send a POST request with malicious script tags in the 'name' or 'email' fields. This script would then be saved to the database and could be executed in the browser of anyone who views this data, leading to potential data theft or other malicious activity.

To mitigate this vulnerability, it is crucial to add validation and sanitization for all incoming requests to ensure that only valid and safe data is stored in the database.

Steps​

  • Validate the input data: Ensure that the data received from the user is valid. This can be done by checking the data type, length, format, and range.
  • Sanitize the input data: Remove any unwanted characters or code that could be used in an XSS attack. This can be done using a library or function that is designed for this purpose.
  • Use prepared statements or parameterized queries: This can help to prevent SQL injection attacks by ensuring that user input is never directly included in a SQL query.
  • Implement Content Security Policy (CSP): This can help to mitigate the risk of XSS attacks by specifying the domains that the browser should consider to be valid sources of executable scripts.
  • Set the requestValidationMode to 2.0 or higher in the server configuration files: This will enable request validation, which can help to prevent XSS attacks by automatically validating user input.

Compliant code​

use Illuminate\\Http\\Request;
use Illuminate\\Support\\Facades\\Validator;

Route::post('/user/update', function (Request $request) {
    $validator = Validator::make($request->all(), [
        'name' => 'required|string|max:255',
        'email' => 'required|string|email|max:255|unique:users,email,' . Auth::id(),
    ]);

    if ($validator->fails()) {
        return redirect('/user/profile')
            ->withErrors($validator)
            ->withInput();
    }

    $user = Auth::user();
    $user->name = e($request->input('name'));
    $user->email = e($request->input('email'));
    $user->save();

    return redirect('/user/profile');
});

The updated code now includes input validation and sanitization to prevent XSS attacks.

The Validator::make function is used to validate the user input. It checks if the 'name' and 'email' fields are present, are strings, and do not exceed 255 characters. For the 'email' field, it also checks if the input is in a valid email format and is unique in the 'users' table, excluding the current user's email.

If the validation fails, the user is redirected back to the profile page with the validation errors and the input they had entered.

The e function is used to sanitize the user input. It converts all applicable characters to HTML entities, which helps prevent XSS attacks by ensuring that any scripts in the user input are not executed.

The Auth::user() function is used to get the currently authenticated user, and the user's name and email are updated with the validated and sanitized input.

Finally, the user's information is saved and the user is redirected back to the profile page.

References​

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