Lack of data validation

Lack of data validation - Responses

Need

Implementation of robust data validation for response data

Context

• Usage of Go 1.16 for building efficient and scalable applications

• Usage of Gin framework for building web applications in Go

Description

1. Non compliant code

package main

import (
	"github.com/gin-gonic/gin"
)

type User struct {
	Name string `json:"name"`...

The above Go code represents a simple backend application using the Gin framework. It has two endpoints. The first endpoint `/user/:id` is a GET method that retrieves the user's information based on the user id passed in the URL. The second endpoint `/updateUser` is a POST method that updates the user's information based on the JSON data sent in the request body. The vulnerability here lies in the `/updateUser` endpoint. The endpoint takes the user's information from the request without validating the data. This means that if a response from the `/user/:id` endpoint is manipulated and sent as a request to the `/updateUser` endpoint, the application will accept the manipulated data without any validation. For example, if a malicious actor changes the user's ID in the response from the `/user/:id` endpoint to an invalid ID and sends it as a request to the `/updateUser` endpoint, the application will update the user's information with the invalid ID without any validation. This can lead to various issues such as data inconsistency or even data corruption.

2. Steps

• Implement data validation on the server-side to ensure the integrity and validity of the received data.

• Validate the data received in the POST `/updateUser` endpoint before updating the user data in the database.

• Use appropriate validation techniques such as input sanitization, data type validation, length validation, and format validation.

• Handle validation errors properly and return meaningful error messages to the client.

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

• Avoid relying solely on client-side validation as it can be bypassed.

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

3. Secure code example

package main

import (
	"github.com/gin-gonic/gin"
	"github.com/go-playground/validator/v10"
)

	ID   string `json:"id" validate:"required,uuid"`...

The updated code now includes data validation for the `User` struct using the `validator` package. The `User` struct now includes `validate` tags that specify the validation rules for each field. The `ID` field is required and must be a valid UUID, and the `Name` field is required. In the `main` function, a new `validator.Validate` instance is created and assigned to the global `validate` variable. This instance is used to validate the `User` data in the `POST /updateUser` endpoint. In the `POST /updateUser` endpoint, after binding the JSON request body to the `User` struct, the `User` data is validated using the `validate.Struct` method. If the validation fails, an error message is returned to the client with a 400 status code, and the function returns immediately. If the validation succeeds, the user data is updated in the database. This update ensures that only valid `User` data is accepted and processed by the server, preventing potential issues caused by invalid data.

References

• 191. Lack of data validation - Responses

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