Bola Idor in Echo Go

BOLA (Broken Object Level Authorization) and IdOR (Insecure Direct Object Reference) vulnerabilities in Echo Go typically emerge from improper access controls on resource identifiers. In Echo Go applications, these vulnerabilities often appear in CRUD operations where the framework's parameter binding automatically extracts IDs from URLs without validating whether the authenticated user owns or can access the referenced resource.

Consider a typical Echo Go route pattern:

e.GET("/users/:id", getUserByID)

The id parameter is automatically bound to the function signature:

func getUserByID(c echo.Context) error {
    id := c.Param("id")
    user, err := db.GetUserByID(id)
    if err != nil {
        return err
    }
    return c.JSON(http.StatusOK, user)
}

This pattern is vulnerable because any authenticated user can request /users/1, /users/2, etc., regardless of ownership. The database query executes without verifying that the requesting user has permission to view the target user's data.

A more subtle manifestation occurs in nested resources:

e.GET("/users/:userID/posts/:postID", getPost)

Here, an attacker might manipulate the userID parameter to access posts from other users while keeping a valid postID. The Echo Go parameter binding makes it trivial to extract these values, but developers often forget to validate ownership across both dimensions.

Echo Go's middleware system can exacerbate this issue. When using JWT middleware, the decoded token is available in the context, but developers frequently access it incorrectly:

func getPost(c echo.Context) error {
    postID := c.Param("postID")
    userID := c.Param("userID") // WRONG: this is the URL param, not the authenticated user
    
    post, err := db.GetPost(postID, userID)
    if err != nil {
        return err
    }
    return c.JSON(http.StatusOK, post)
}

The vulnerability here is that userID comes from the URL parameter, not the authenticated user's ID. An attacker can simply change the URL to access any user's posts.

Detecting BOLA/IdOR vulnerabilities in Echo Go applications requires both static analysis and dynamic testing. Static analysis can identify patterns where parameters are extracted without ownership validation, while dynamic testing attempts to access resources across user boundaries.

Using middleBrick's CLI for Echo Go applications provides immediate detection without modifying your codebase:

middlebrick scan https://your-echo-app.com/api/users/1

The scanner automatically tests parameter manipulation patterns specific to Go applications, including:

• Sequential ID enumeration across user resources
• Nested resource boundary testing
• Cross-tenant data access attempts
• Authorization bypass through parameter tampering

For Echo Go specifically, middleBrick analyzes the OpenAPI spec if available and maps parameter extraction patterns to runtime behavior. The scanner tests 12 security categories in parallel, with BOLA/IdOR detection focusing on resource ownership validation failures.

Manual detection in Echo Go code involves searching for these patterns:

# Find parameter extraction without authorization checks
grep -r "c.Param(" . --include="*.go" | grep -v "authorize"

Look for handler functions that extract IDs but don't validate against the authenticated user's context. Pay special attention to:

• Database queries using URL parameters directly
• Middleware that decodes JWT but doesn't propagate user context
• Functions with multiple ID parameters where only one is validated

Echo Go's Context interface makes it easy to store user information during middleware processing:

func JWTAuth(next echo.HandlerFunc) echo.HandlerFunc {
    return func(c echo.Context) error {
        token := extractToken(c)
        claims := parseJWT(token)
        c.Set("user_id", claims.UserID) // Store for later validation
        return next(c)
    }
}

Detection should verify that downstream handlers actually use this stored value for authorization rather than trusting URL parameters.

Remediating BOLA/IdOR vulnerabilities in Echo Go requires a systematic approach to authorization that validates resource ownership at every access point. The most effective pattern uses Echo Go's middleware and context features to enforce consistent authorization.

First, create a middleware that validates resource ownership:

func authorizeResource(next echo.HandlerFunc, resourceID string, resourceType string) echo.HandlerFunc {
    return func(c echo.Context) error {
        userID := c.Get("user_id").(string)
        authorized, err := db.CheckOwnership(userID, resourceID, resourceType)
        if err != nil || !authorized {
            return echo.NewHTTPError(http.StatusForbidden, "Access denied")
        }
        return next(c)
    }
}

Apply this middleware to vulnerable routes:

e.GET("/users/:id", authorizeResource(getUserByID, ":id", "user"))
e.GET("/users/:userID/posts/:postID", authorizeResource(getPost, ":postID", "post"))

For nested resources, you need authorization at multiple levels:

e.GET("/users/:userID/posts/:postID", func(c echo.Context) error {
    userID := c.Param("userID")
    postID := c.Param("postID")
    
    // Validate both user and post ownership
    if !db.UserExists(userID) {
        return echo.NewHTTPError(http.StatusNotFound, "User not found")
    }
    
    post, err := db.GetPostWithAuthorization(postID, userID)
    if err != nil {
        return echo.NewHTTPError(http.StatusNotFound, "Post not found or access denied")
    }
    
    return c.JSON(http.StatusOK, post)
})

Echo Go's Validator interface can help prevent parameter tampering:

type CustomValidator struct{}

func (cv *CustomValidator) Validate(i interface{}) error {
    return echo.NewHTTPError(http.StatusBadRequest, "Invalid input")
}

// Register validator
e.Validator = &CustomValidator{}

This ensures that only properly formatted parameters reach your handlers, though it doesn't replace authorization checks.

For database queries, use parameterized queries with ownership validation:

func GetPostWithAuthorization(postID string, userID string) (*Post, error) {
    query := "SELECT * FROM posts WHERE id = $1 AND user_id = $2"
    row := db.QueryRow(query, postID, userID)
    
    var post Post
    err := row.Scan(&post.ID, &post.Content, &post.UserID)
    if err != nil {
        return nil, err
    }
    return &post, nil
}

This pattern ensures that even if an attacker manipulates the URL, the database query will only return results where the ownership matches, preventing data leakage.