Fix Mass Assignment in Iris
Mass Assignment in Iris occurs when you blindly bind raw HTTP request bodies directly to your database models. If your 'User' struct contains a 'Role' or 'IsAdmin' field and you pass it straight to ctx.ReadJSON(), a malicious actor can escalate privileges by simply adding '"is_admin": true' to their JSON payload. This is a critical failure in data sanitization and model encapsulation.
The Vulnerable Pattern
type User struct { ID uint `json:"id"` Username string `json:"username"` IsAdmin bool `json:"is_admin"` }
func RegisterHandler(ctx iris.Context) { var user User // VULNERABILITY: ReadJSON binds directly to the DB model. // Attacker sends: {“username”: “hacker”, “is_admin”: true} if err := ctx.ReadJSON(&user); err != nil { ctx.StopWithStatus(iris.StatusBadRequest) return } db.Create(&user) }
The Secure Implementation
The fix involves decoupling your API interface from your persistence layer. By implementing a DTO (Data Transfer Object) or a 'Request' struct, you define a strict allow-list of fields that the user is permitted to modify. Even if the attacker sends extra fields in the JSON body, the Iris binder will ignore them because they aren't defined in the DTO. Always treat input as untrusted and use explicit mapping to populate your database entities.
type UserCreateDTO struct { Username string `json:"username"` }func RegisterHandler(ctx iris.Context) { var input UserCreateDTO // SECURE: Bind to a Data Transfer Object (DTO) instead of the model. if err := ctx.ReadJSON(&input); err != nil { ctx.StopWithStatus(iris.StatusBadRequest) return }
// Explicitly map fields to the DB model newUser := User{ Username: input.Username, IsAdmin: false, // Hardcoded or handled by internal logic only } db.Create(&newUser)
}
Your Iris API
might be exposed to Mass Assignment
74% of Iris apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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