Your Backend Trusts Your App Too Much

Most systems assume:

“Requests coming from our app are safe.”

That assumption breaks quickly.

Mobile apps handle validation, flows, and restrictions — but the client environment is controllable. Requests can be modified, replayed, or triggered outside the UI.

The real issue isn’t missing validation — it’s misplaced trust.

What goes wrong

• Client-side validation gets bypassed
• Flows are executed out of sequence
• Parameters are tampered
• Requests are replayed

Example

❌ Vulnerable:

if (req.isKycVerified) {
    generateLink();
}

Client controls this flag.

✅ Correct:

User user = repo.find(req.userId);

if (user.getKycStatus() == VERIFIED) {

    generateLink();

}

What to fix

• Backend must be the source of truth
• Validate all critical data server-side
• Enforce flows on backend
• Add idempotency for sensitive operations

Key takeaway

UI constraints are not security controls.

👉 Full breakdown on Medium
https://medium.com/@vaibhav.shakya786/your-backend-trusts-your-app-too-much-heres-how-attackers-abuse-that-670af5c9b1a3