Fix BOLA (Broken Object Level Authorization) in Gorilla
BOLA (formerly IDOR) remains the #1 threat in the OWASP API Top 10. In Gorilla mux, the vulnerability manifests when a developer extracts a resource ID from `mux.Vars(r)` and queries the database without verifying if the authenticated user has permission to access that specific object. If you're fetching data based solely on a URL parameter, you're leaking data.
The Vulnerable Pattern
func GetOrder(w http.ResponseWriter, r *http.Request) { vars := mux.Vars(r) orderID := vars["id"]var order Order // VULNERABLE: Direct object reference without ownership verification err := db.QueryRow("SELECT id, total, status FROM orders WHERE id = ?", orderID).Scan(&order.ID, &order.Total, &order.Status) if err != nil { http.Error(w, "Not Found", http.StatusNotFound) return } json.NewEncoder(w).Encode(order)
}
The Secure Implementation
To kill BOLA, you must implement fine-grained access control. First, ensure your authentication middleware injects the user's identity into the request context. Second, never trust the `{id}` from the Gorilla router as the sole key for a lookup. Always include the authenticated `userID` in your SQL `WHERE` clause or perform a manual ownership check before returning the object. This ensures that even if an attacker guesses a valid UUID/ID, the database will return zero rows because the ownership doesn't match the session.
func GetOrder(w http.ResponseWriter, r *http.Request) { vars := mux.Vars(r) orderID := vars["id"]// Retrieve authenticated UserID from context (populated by Auth Middleware) userID, ok := r.Context().Value("userID").(string) if !ok { http.Error(w, "Unauthorized", http.StatusUnauthorized) return } var order Order // SECURE: Query includes the owner_id to enforce authorization at the database level query := "SELECT id, total, status FROM orders WHERE id = ? AND user_id = ?" err := db.QueryRow(query, orderID, userID).Scan(&order.ID, &order.Total, &order.Status) if err == sql.ErrNoRows { // Return 403 or 404 to prevent ID enumeration http.Error(w, "Access Denied", http.StatusForbidden) return } json.NewEncoder(w).Encode(order)
}
Your Gorilla API
might be exposed to BOLA (Broken Object Level Authorization)
74% of Gorilla apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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