Insecure Direct Object Reference in Buffalo with Jwt Tokens

Remediation centers on enforcing authorization after authentication. After decoding Jwt Tokens to identify the subject, the handler must scope data access so that users can only interact with resources they own or are permitted to access. Below are concrete, idiomatic Buffalo Go examples that demonstrate secure patterns.

1. Load subject from validated Jwt Tokens and enforce ownership

Assume Jwt Tokens contain a sub claim identifying the user. Decode the token, extract the subject, and use it to scope the query:

// handlers/articles.go
import (
    "github.com/gobuffalo/buffalo"
    "github.com/gobuffalo/packr/v2"
    "github.com/golang-jwt/jwt/v4"
    "yourapp/models"
)

func ArticlesShow(c buffalo.Context) error {
    // Assume JWT is validated by middleware and user info is placed in context
    userID, ok := c.Value("user_id").(string)
    if !ok {
        return c.Error(401, errors.New("unauthorized"))
    }

    id := c.Params().Get("id")
    var article Article
    // Enforce ownership: only fetch if article belongs to userID
    if err := models.DB().Where("user_id = ? AND id = ?", userID, id).First(&article); err != nil {
        return c.Error(404, errors.New("not found"))
    }
    return c.Render(200, r.JSON(article))
}

This ensures that even if an attacker changes the id, the database query will return no rows unless the article belongs to that specific user, effectively mitigating BOLA/IDOR.

2. Use UUID-based public IDs with ownership checks

Instead of exposing sequential integers, use UUIDs and validate access:

// handlers/articles.go
import (
    "github.com/gobuffalo/buffalo"
    "github.com/satori/go.uuid"
)

func ArticlesShow(c buffalo.Context) error {
    userID, _ := c.Value("user_id").(string)
    rawID := c.Params().Get("id")
    articleID, err := uuid.FromString(rawID)
    if err != nil {
        return c.Error(400, errors.New("invalid id"))
    }
    var article Article
    if err := models.DB().Where("user_id = ? AND id = ?", userID, articleID).First(&article); err != nil {
        return c.Error(404, errors.New("not found"))
    }
    return c.Render(200, r.JSON(article))
}

3. Centralize authorization logic

To avoid repetition, implement a helper that scopes queries by subject derived from Jwt Tokens:

// models/query.go
package models

import (
    "github.com/gobuffalo/buffalo"
    "github.com/golang-jwt/jwt/v4"
)

func ScopedQuery(c buffalo.Context, model interface{}) (*gorm.DB, error) {
    userID, ok := c.Value("user_id").(string)
    if !ok {
        return nil, errors.New("unauthorized")
    }
    // Example: assuming model implements an interface with TenantID()
    // or using a global where clause for multi-tenant safety
    db := DB().Where("user_id = ?", userID)
    return db, nil
}

// Usage in handler:
// db, err := ScopedQuery(c, &Article{})
// if err != nil { return c.Error(401, err) }
// db.First(&article, id)

These patterns ensure that Jwt Tokens are not merely used for authentication but also inform authorization decisions, directly addressing BOLA/IDOR risks. middleBrick’s scans can verify whether such scoping checks exist by correlating endpoint behavior with the declared authentication mechanisms.