Need

Enforce proper data validation to prevent out-of-range access

Context

• Usage of Go 1.15 for building efficient 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"
)

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

    r.GET("/restricted/employeeManagement", func(c *gin.Context) {
        c.String(200, "Employee Management Page")
    })

    r.Run()
}
        
        

This simple Gin application has a single route /restricted/employeeManagement which is supposed to be a restricted page, such as Employee Management.

The vulnerability lies in the fact that there is no validation or access control for this route. Any authenticated user, regardless of their permissions or role, can access this route simply by requesting the absolute path /restricted/employeeManagement.

This means that a user with restricted permissions could potentially bypass their restrictions and access functionalities that they are not supposed to. This constitutes a serious security vulnerability as it allows for privilege escalation.

Steps

• Implement proper authentication and authorization mechanisms to ensure that only authorized users can access restricted functionalities.
• Validate the user's permissions before allowing access to restricted functionalities.
• Use a role-based access control (RBAC) system to define and enforce user permissions.
• Implement input validation to ensure that the requested functionality is within the allowed range of actions for the authenticated user.
• Consider using a middleware to handle the authentication and authorization logic for all routes that require restricted access.

Compliant code

        package main

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

type User struct {
    Role string
}

func AuthRequired() gin.HandlerFunc {
    return func(c *gin.Context) {
        user, _ := c.Get("user")
        if user == nil {
            c.AbortWithStatusJSON(401, gin.H{"error": "Unauthorized"})
            return
        }

        if user.(*User).Role != "admin" {
            c.AbortWithStatusJSON(403, gin.H{"error": "Forbidden"})
            return
        }

        c.Next()
    }
}

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

    r.Use(func(c *gin.Context) {
        // This is just a placeholder for actual authentication logic
        user := &User{Role: "admin"}
        c.Set("user", user)
    })

    authorized := r.Group("/restricted")
    authorized.Use(AuthRequired())
    authorized.GET("/employeeManagement", func(c *gin.Context) {
        c.String(200, "Employee Management Page")
    })

    r.Run()
}
        
        

The updated code includes an authentication middleware that checks if a user is authenticated and authorized to access the restricted functionalities.

The AuthRequired function is a middleware that checks if the user is authenticated and has the necessary role to access the restricted functionalities. If the user is not authenticated, it returns a 401 Unauthorized status. If the user is authenticated but does not have the necessary role, it returns a 403 Forbidden status.

In the main function, we use the Use function to add the authentication middleware to the Gin engine. This middleware sets a placeholder user with the role of "admin". This is just a placeholder and should be replaced with actual authentication logic.

We then create a new route group for the restricted routes using the Group function. We add the AuthRequired middleware to this group using the Use function. This ensures that the AuthRequired middleware is run for all routes in this group.

Finally, we add the /employeeManagement route to the restricted group. This route is now protected by the AuthRequired middleware and can only be accessed by authenticated users with the necessary role.

References

• 198. Lack of data validation - Out of range