Fix Logic Flow Bypass in Micronaut
Logic flow bypasses in Micronaut occur when an application fails to enforce the correct sequence of operations, allowing an attacker to skip critical steps like payment verification or MFA. In Micronaut's reactive ecosystem, developers often rely on URL-level security while ignoring server-side state management. To mitigate this, you must implement a strict state machine that validates the transition context before executing business logic.
The Vulnerable Pattern
@Controller("/order")
public class OrderController {
@Post("/process")
@Secured(SecurityRule.IS_AUTHENTICATED)
public HttpResponse processOrder(@Body OrderRequest request) {
// VULNERABILITY: Trusting the client to call /pay before /process
// An attacker can POST directly here and bypass the payment step
orderService.finalize(request);
return HttpResponse.ok("Order Shipped");
}
}The Secure Implementation
The vulnerable code assumes that because a user is authenticated, they have followed the intended UI flow. A 'hacker' simply intercepts the traffic and hits the /process endpoint directly. The fix involves implementing a server-side state machine (via StateService). Before the final action is taken, the application queries a trusted data store (Redis, SQL, etc.) to verify that the prerequisite state (PAYMENT_CONFIRMED) was actually reached. If the sequence is out of order, the request is dropped with a 403 Forbidden.
@Controller("/order") public class OrderController { private final StateService stateService;@Post("/process") @Secured(SecurityRule.IS_AUTHENTICATED) public HttpResponse<?> processOrder(@Body OrderRequest request, Authentication auth) { String userId = auth.getName(); OrderState currentState = stateService.get(userId, request.getOrderId()); // SECURE: Enforce state transition. Only allow 'PAID' orders to be processed. if (currentState != OrderState.PAYMENT_CONFIRMED) { return HttpResponse.status(HttpStatus.FORBIDDEN).body("Invalid state transition: Payment required."); } orderService.finalize(request); stateService.update(userId, request.getOrderId(), OrderState.COMPLETED); return HttpResponse.ok("Order Shipped"); }
}
Your Micronaut API
might be exposed to Logic Flow Bypass
74% of Micronaut apps fail this check. Hackers use automated scanners to find this specific flaw. Check your codebase before they do.
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