Insecure object reference

Need

Secure and robust authorization mechanism to prevent unauthorized access to sensitive data

Context

• Usage of Go 1.16 for building high-performance and scalable applications
• Usage of gin-gonic/gin for building web applications and APIs in Go

Description

Non compliant code

package main

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

type User struct {
	ID    int    `json:"id"`
	Name  string `json:"name"`
	Email string `json:"email"`
}

var users = []User{
	{ID: 1, Name: "John Doe", Email: "[email protected]"},
	{ID: 2, Name: "Jane Doe", Email: "[email protected]"},
}

func main() {
	r := gin.Default()

	r.GET("/user/:id", func(c *gin.Context) {
		id := c.Param("id")

		for _, user := range users {
			if user.ID == id {
				c.JSON(200, user)
				return
			}
		}

		c.JSON(404, gin.H{"message": "User not found"})
	})

	r.Run()
}

The code above is a simple Go server using the Gin framework, which has a vulnerability of Insecure Direct Object Reference (IDOR). The server has a route /user/:id that fetches and returns user data based on the user's ID.

The vulnerability lies in the fact that there is no authorization mechanism in place to check if the user requesting the data is allowed to access it. Any user can access the data of any other user just by changing the id parameter in the URL.

For example, if a user with ID 1 knows the URL structure, they can easily access the data of the user with ID 2 by sending a GET request to /user/2. This can lead to unauthorized access to sensitive user data and is a serious security risk.

To fix this vulnerability, an authorization check should be added to ensure that the user requesting the data is the same as the user whose data is being requested.

Steps

• Implement proper authentication and authorization mechanisms to ensure that users can only access their own data.
• Use a secure and unique identifier for each user, such as a UUID, instead of using the user's ID as a parameter in the URL.
• Validate the user's identity and permissions before retrieving or modifying any data.
• Ensure that sensitive data is properly protected, such as encrypting user email addresses.
• Regularly update and patch the application and its dependencies to address any security vulnerabilities.

Compliant code

package main

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

type User struct {
	ID    uuid.UUID `json:"id"`
	Name  string    `json:"name"`
	Email string    `json:"email"`
}

var users = []User{
	{ID: uuid.Must(uuid.NewV4()), Name: "John Doe", Email: "[email protected]"},
	{ID: uuid.Must(uuid.NewV4()), Name: "Jane Doe", Email: "[email protected]"},
}

func main() {
	r := gin.Default()

	r.GET("/user/:id", func(c *gin.Context) {
		id, err := uuid.FromString(c.Param("id"))
		if err != nil {
			c.JSON(400, gin.H{"message": "Invalid user ID"})
			return
		}

		for _, user := range users {
			if user.ID == id {
				// TODO: Add authentication and authorization checks here
				c.JSON(200, user)
				return
			}
		}

		c.JSON(404, gin.H{"message": "User not found"})
	})

	r.Run()
}

The original code was vulnerable to insecure object reference as it used the user's ID as a parameter in the URL, which could be easily manipulated to access another user's data.

The fixed code addresses this vulnerability by implementing several changes:

1. UUID as User Identifier: Instead of using the user's ID as a parameter in the URL, a UUID (Universally Unique Identifier) is used. UUIDs are secure and unique, making it difficult for an attacker to guess or manipulate.

2. Input Validation: The user's ID is validated before it is used. If the ID is not a valid UUID, an error message is returned.

3. Authentication and Authorization Checks: A placeholder for authentication and authorization checks is added. These checks should verify the user's identity and permissions before any data is retrieved or modified.

4. Sensitive Data Protection: Although not shown in the code, it is recommended to encrypt sensitive user data such as email addresses to further enhance data protection.

5. Regular Updates and Patches: Regularly updating and patching the application and its dependencies can help address any security vulnerabilities that may arise in the future.

References

• 013.Insecure object reference