Skip to main content

Insecure object reference - Corporate information

Need​

Secure handling of object references and access control for corporate information

Context​

  • Usage of Go 1.16 for developing high-performance and concurrent applications
  • Usage of Gin framework for building web applications in Go
  • Usage of encoding/csv for reading and writing CSV files
  • Usage of the os module for operating system related functionalities

Description​

Non compliant code​

package main

import (
	"github.com/gin-gonic/gin"
	"encoding/csv"
	"os"
)

type Employee struct {
	PayrollNumber string
	FirstName     string
	LastName      string
	Company       string
}

var Employees []Employee

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

	r.POST("/upload", func(c *gin.Context) {
		file, _ := c.FormFile("file")
		f, _ := file.Open()

		reader := csv.NewReader(f)
		records, _ := reader.ReadAll()

		for _, record := range records {
			Employees = append(Employees, Employee{
				PayrollNumber: record[0],
				FirstName:     record[1],
				LastName:      record[2],
				Company:       record[3],
			})
		}

		c.String(200, "File uploaded successfully")
	})

	r.Run()
}

The above code represents a simple Go application using the Gin framework. It accepts a POST request at the "/upload" endpoint which expects a file to be uploaded. The file is expected to be a CSV file containing records of employees.

The vulnerability lies in the fact that the application does not verify the authenticity of the uploaded file nor does it check if the user has the necessary permissions to add or modify employee records.

The uploaded file is read and its contents are appended to the Employees slice without any checks. This means that an attacker can upload a file containing information about employees of a third party company and modify the PayrollNumber to one that they do not have access to. This would result in the information being stored in the third party company, associating new employees or updating the information of those that already existed.

The lack of proper access control and input validation makes this application vulnerable to insecure object reference attacks.

Steps​

  • Implement authentication and authorization mechanisms to ensure that only authorized users can upload employee information.
  • Validate the uploaded file to ensure it is in the expected format (e.g., Excel file) and contains the necessary fields.
  • Implement input validation to ensure that the payroll number and other employee information are properly formatted and meet the required criteria.
  • Verify the company identifier (payroll number) against the authenticated user's access rights to prevent unauthorized modification of employee information for other companies.
  • Consider using a database or other secure storage mechanism to store employee information instead of keeping it in memory (e.g., the 'Employees' slice).
  • Encrypt sensitive employee information (e.g., payroll number) to protect it from unauthorized access or disclosure.
  • Regularly update and patch the dependencies (e.g., Gin framework) used in the application to ensure any security vulnerabilities are addressed.
  • Perform security testing and code reviews to identify and fix any other potential vulnerabilities in the application.

Compliant code​

package main

import (
	"github.com/gin-gonic/gin"
	"encoding/csv"
	"os"
	"errors"
)

type Employee struct {
	PayrollNumber string
	FirstName     string
	LastName      string
	Company       string
}

var Employees []Employee

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

	r.Use(AuthMiddleware()) // Add authentication middleware

	r.POST("/upload", func(c *gin.Context) {
		user, _ := c.Get("user") // Get authenticated user

		file, err := c.FormFile("file")
		if err != nil {
			c.String(400, "Invalid file format")
			return
		}

		f, _ := file.Open()

		reader := csv.NewReader(f)
		records, err := reader.ReadAll()
		if err != nil {
			c.String(400, "Invalid file content")
			return
		}

		for _, record := range records {
			employee := Employee{
				PayrollNumber: record[0],
				FirstName:     record[1],
				LastName:      record[2],
				Company:       record[3],
			}

			if !validateEmployee(employee, user) {
				c.String(403, "Unauthorized access")
				return
			}

			Employees = append(Employees, employee)
		}

		c.String(200, "File uploaded successfully")
	})

	r.Run()
}

func AuthMiddleware() gin.HandlerFunc {
	// Implement your authentication logic here
	return func(c *gin.Context) {
		// ...
	}
}

func validateEmployee(employee Employee, user interface{}) bool {
	// Implement your validation logic here
	return true
}

The updated code includes several security enhancements to address the insecure object reference vulnerability:

  1. Authentication Middleware: The AuthMiddleware function is used to authenticate users before they can access the /upload endpoint. This ensures that only authorized users can upload employee information.

  2. File Validation: The uploaded file is validated to ensure it is in the correct format and contains valid content. If the file format or content is invalid, a 400 status code is returned.

  3. Employee Validation: The validateEmployee function is used to validate the employee information before it is added to the Employees slice. This function checks that the payroll number and other employee information are properly formatted and meet the required criteria. It also verifies the company identifier (payroll number) against the authenticated user's access rights to prevent unauthorized modification of employee information for other companies.

  4. Error Handling: The code includes error handling to return appropriate status codes and messages when an error occurs. This helps to prevent information leakage and provides a better user experience.

Please note that the AuthMiddleware and validateEmployee functions are placeholders and need to be implemented with your own authentication and validation logic. Also, consider using a database or other secure storage mechanism to store employee information instead of keeping it in memory (e.g., the 'Employees' slice), and encrypt sensitive employee information (e.g., payroll number) to protect it from unauthorized access or disclosure. Regularly update and patch the dependencies (e.g., Gin framework) used in the application to ensure any security vulnerabilities are addressed. Perform security testing and code reviews to identify and fix any other potential vulnerabilities in the application.

References​

Last updated on