How to fix BOLA (Broken Object Level Authorization)
in Vapor (Swift)
Executive Summary
Broken Object Level Authorization (BOLA) remains the top threat in API security. In the Vapor (Swift) ecosystem, this typically manifests when developers fetch models directly via ID parameters without validating ownership against the authenticated user session. If you are querying `.find(id)` without a secondary filter on `user_id`, you are effectively handing over your database to any script kiddie with a Burp Suite instance.
The Vulnerable Pattern
func getNote(req: Request) throws -> EventLoopFuture {
let noteID = try req.parameters.require("noteID", as: UUID.self)
// VULNERABLE: Fetches any note by ID regardless of who owns it
return Note.find(noteID, on: req.db)
.unwrap(or: Abort(.notFound))
} The Secure Implementation
The fix involves moving from a direct ID lookup to a scoped query. By utilizing Fluent's `.filter` chain, we enforce that the record's foreign key matches the authenticated user's primary key. Returning a 404 instead of a 403 for unauthorized access is preferred here to prevent 'Resource Enumeration'—leaking the fact that a specific ID actually exists in the system.
func getNote(req: Request) throws -> EventLoopFuture{ let user = try req.auth.require(User.self) let noteID = try req.parameters.require("noteID", as: UUID.self) // SECURE: Scopes the query to the authenticated user's ID return Note.query(on: req.db) .filter(\.$id == noteID) .filter(\.$user.$id == try user.requireID()) .first() .unwrap(or: Abort(.notFound))
}
Your Vapor (Swift) API
might be exposed to BOLA (Broken Object Level Authorization)
74% of Vapor (Swift) apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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