INSECURE MODE — CAPTCHA is NOT invalidated after use, no rate limiting
Phase 1The Business Request — Where it all begins

SecureBank — Online Banking Portal

SecureBank operates a comprehensive online banking portal serving 2M+ customers. The portal currently supports account management, fund transfers, bill payments, and investment services. The bank is now expanding its digital services to improve customer satisfaction.

Existing Online Banking Portal

Account DashboardLive
Fund TransfersLive
Bill PaymentsLive
Investment ServicesLive
Loan ApplicationsLive
Customer ComplaintsNEW

Business Stakeholder Request

VP of Customer Experience

"We're receiving too many customer complaints via email and phone. We need a digital complaint submission system integrated into our online banking portal. Customers should be able to submit complaints directly, and we need to prevent spam submissions. This should be available to all authenticated banking customers."

Business Requirements Document (BRD)

BRD-2024-0847 — Customer Complaint Portal Module

BR-01

Digital Complaint Submission

Customers shall be able to submit complaints through the online banking portal with a structured form including subject, description, and severity rating.

BR-02

Spam Prevention

The system shall implement CAPTCHA verification to prevent automated spam submissions to the complaint system.

BR-03

Customer Authentication

Only authenticated banking customers shall be able to access and submit complaints through the portal.

BR-04

Complaint Tracking

Each complaint shall be assigned a unique reference number and stored in the banking database for tracking and resolution.

BR-05

Notification

The system shall notify the assigned relationship manager when a new complaint is submitted.

Key Observation

Notice that the business requirements mention "CAPTCHA verification" and "authenticated customers" — but they don't specify how many times a customer can submit, or whether the CAPTCHA should be single-use. This ambiguity is where the business logic flaw begins.