How I Would Fix exposed API keys and missing auth in a React Native and Expo paid acquisition funnel Using Launch Ready.

How I Would Fix exposed API keys and missing auth in a React Native and Expo paid acquisition funnel Using Launch Ready

If I see exposed API keys and missing auth in a React Native and Expo paid acquisition funnel, I assume two things at once: the app is already leaking trust, and the funnel is probably paying to send traffic into a broken backend. The most likely root cause is that secrets were placed in the client bundle, while protected endpoints were built as if the frontend would "behave" instead of enforcing access server-side.

The first thing I would inspect is the actual attack surface: the shipped app bundle, the network calls from onboarding and checkout screens, and the backend routes that create leads, start trials, or unlock paid features. In business terms, this is not just a security issue. It can turn into fake signups, unauthorized usage, support load, ad spend waste, and possible customer data exposure.

Triage in the First Hour

1. Pull the latest production build details.

• Confirm the Expo release channel, EAS build number, and store version.
• Check whether the bad build is live on iOS, Android, or both.

2. Inspect the client bundle for secrets.

• Search for API keys, private URLs, service tokens, Firebase config misuse, Stripe secret usage, or admin endpoints.
• Check `.env`, `app.config.js`, `eas.json`, and any hardcoded values in screens or utility files.

3. Review network traffic from the funnel flow.

• Open onboarding, signup, payment intent creation, lead capture, and post-purchase unlock requests.
• Verify whether requests rely only on client-side checks like hidden buttons or local state.

4. Check authentication enforcement on backend routes.

• Confirm every paid-only route validates a session token or server-issued entitlement.
• Look for endpoints that return premium content without checking identity or subscription status.

5. Review logs and error dashboards.

• Look for unusual request volume, repeated 401/403 failures, rate spikes, or suspicious IP patterns.
• Check whether secrets may have been used outside normal geography or traffic patterns.

6. Inspect deployment and secret management.

• Confirm secrets are stored in environment variables or a vault, not in source code.
• Review Cloudflare settings if traffic protection or bot filtering is already available.

7. Verify app store builds and over-the-air updates.

• Check whether an older insecure bundle is still being served through EAS Update or cached by users.

8. Freeze risky changes until containment is clear.

• Stop new feature merges into the funnel until auth boundaries are fixed.
• If needed, disable exposed endpoints temporarily rather than letting them continue to leak.

## Quick search for likely secret leaks
grep -RniE "sk_live|sk_test|api_key|secret|token|private_key|Bearer " .

## Check env exposure in Expo config
cat app.config.* eas.json .env* 2>/dev/null

Root Causes

1. Secrets were bundled into the mobile app.

• Common when a founder uses `EXPO_PUBLIC_` for values that should never be public.
• Confirm by decompiling the JS bundle or searching compiled assets for key strings.

2. Backend routes trust the client too much.

• The app may hide premium screens locally but never verifies access on the server.
• Confirm by calling protected endpoints with a fresh token removed or expired.

3. A third-party service was wired directly from the app.

• Examples include database admin access, email providers, analytics write keys with broad permissions, or payment secrets embedded in screens.
• Confirm by tracing where each key is used and whether it has write or admin scope.

4. Auth exists but is only cosmetic.

• The UI may require login visually while API responses still return data without checking identity.
• Confirm by testing direct endpoint calls outside the app flow.

5. Environment separation is broken.

• Dev keys may have been shipped to production because staging and prod variables share names or files.
• Confirm by comparing build-time variables across local, preview, staging, and production.

6. The funnel was built around speed instead of control points.

• Paid acquisition funnels often get rushed: landing page works first, auth gets added later, then nobody revisits permissions before launch.
• Confirm by reviewing commit history and seeing whether security was patched on top of a working demo.

The Fix Plan

My fix plan is to reduce blast radius first, then restore proper access control without breaking conversions.

1. Remove all real secrets from the mobile client.

• Move private API keys to server-side code only.
• If a value must be public in Expo config, treat it as public forever and scope it accordingly.

2. Rotate exposed credentials immediately.

• Regenerate any leaked API keys, tokens, webhook secrets, database passwords, or signing keys.
• Assume anything already shipped is compromised until rotated.

3. Put auth checks behind every sensitive action.

• Enforce authentication on lead creation if it links to paid entitlements.
• Enforce authorization on premium content fetches, account actions, exports, billing actions, and admin flows.

4. Add a backend gate for entitlement checks.

• Do not let the app decide who gets access to paid features by itself.
• Use server-verified session state plus subscription status before returning gated data.

5. Introduce a thin proxy layer if needed.

• If third-party APIs must be called from mobile flows, call them through your own backend endpoint first.
• That lets me validate identity, rate limit abuse, log safely, and hide provider credentials.

6. Lock down CORS only where relevant and do not rely on it as security for mobile apps.

• Mobile apps are not protected by browser assumptions anyway.
• Real security must come from server-side auth and scoped credentials.

7. Add rate limits and abuse controls on funnel endpoints.

• Protect signup forms, OTP requests if used after login starts later), lead capture APIs", "and payment-related endpoints from spam bursts."

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Delivery Map

References

• [roadmap.sh - API security](https://roadmap.sh/api-security-best-practices)
• [OWASP API Security Top 10](https://owasp.org/www-project-api-security/)
• [MDN Web Docs - HTTP](https://developer.mozilla.org/en-US/docs/Web/HTTP)
• [Cloudflare DNS documentation](https://developers.cloudflare.com/dns/)
• [Sentry documentation](https://docs.sentry.io/)

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Take the next step

If this is a problem in your product right now, here is what to do next:

• [Use the free Cyprian tools](/tools) - estimate cost, score app risk, check launch readiness, or pick the right service sprint.

• [Book a discovery call](/contact) - I will tell you honestly whether you need a sprint or if you can DIY the next step.

*Written by Cyprian Tinashe Aarons - senior full-stack and AI engineer helping founders rescue, launch, automate, and scale AI-built products.*