Lack of data validation

Lack of data validation - Responses

Need

Implementation of robust data validation for response data

Context

• Usage of Scala for functional and object-oriented programming in the JVM environment

• Usage of play.api.mvc for handling HTTP requests and responses in Play Framework

Description

1. Non compliant code

import play.api.mvc._

object Application extends Controller {

  def sendResponse = Action { request =>
    val data = request.body.asFormUrlEncoded
    val response = data.get("response").head
  }...

The above Scala code snippet is a simple representation of a Play Framework backend application with two endpoints: `sendResponse` and `receiveResponse`. The `sendResponse` endpoint is accepting a POST request and extracting the `response` parameter from the request body. This `response` is then directly sent back to the client without any data validation. The `receiveResponse` endpoint is also accepting a POST request, but this time it's extracting the `previousResponse` parameter from the request body. This `previousResponse` is supposed to be the response received from the `sendResponse` endpoint. However, again there is no data validation performed here. This code is vulnerable because it blindly trusts the data it receives from the client. If a malicious user modifies the `response` data in the `sendResponse` endpoint or the `previousResponse` data in the `receiveResponse` endpoint to contain invalid or harmful data, the application will accept it without any checks, potentially leading to serious security issues.

2. Steps

• Implement data validation on the response data before using it in subsequent requests.

• Validate the response data against expected formats, data types, and constraints.

• Use appropriate validation techniques such as regular expressions, type checking, or custom validation logic.

• Handle validation errors gracefully and provide meaningful error messages to the user.

• Consider using a validation library or framework to simplify the validation process.

• Ensure that the validation is performed on both the server-side and client-side to provide a robust defense against malicious data.

• Regularly review and update the validation logic to adapt to changing requirements and potential new vulnerabilities.

3. Secure code example

import play.api.mvc._
import play.api.data._
import play.api.data.Forms._

object Application extends Controller {

  case class ResponseData(response: String)
  val responseForm: Form[ResponseData] = Form(...

The updated code includes data validation for the response data. The Play framework's form handling capabilities are used to define a form that maps to a case class `ResponseData`. This form includes a single field, `response`, which is validated as non-empty text. The `sendResponse` and `receiveResponse` methods are updated to use this form. The form data is bound from the request, and the result is either a valid `ResponseData` object or a form with errors. If the form has errors (i.e., the response data is invalid), the `errorFunction` is called, which returns a `BadRequest` response with a message of "Invalid data". If the form is valid, the `successFunction` is called, which returns an `Ok` response with the response data. This approach ensures that invalid response data is not used in subsequent requests, providing a robust defense against malicious data.

References

• 191. Lack of data validation - Responses

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