HackproofHacks
iOS & Android security

Mobile App Penetration Testing

A mobile app is a piece of your backend that you hand directly to your users, and to any attacker who downloads it. Unlike a web app running on your server, the binary sits on a device an attacker fully controls, where they can inspect its storage, intercept its traffic, and reverse-engineer its code at leisure. That changes the threat model, and the testing has to change with it.

This engagement tests your iOS or Android app against the OWASP Mobile Application Security standards, together with the API backend it talks to, because a mobile app is only as secure as the server behind it.

Why mobile apps need their own kind of test

On a device the attacker owns, secrets are not secret by default. Hardcoded API keys, tokens cached in insecure storage, and sensitive data written to logs or local files are all recoverable by someone with the app installed and a little patience. Web testing methods do not cover this device-side attack surface, which is why mobile needs a dedicated methodology.

The bigger risk usually sits behind the app, in the API. Developers sometimes assume the app is the only client and let the backend trust it, but an attacker bypasses the app entirely and calls the API directly with their own tools. If authorization is weak there, the polished app in front of it provides no protection at all.

App-store presence also invites reverse engineering. Anyone can pull your binary apart to understand how it works, find hidden endpoints, and defeat client-side controls like certificate pinning if it is poorly implemented. Testing shows you what an attacker can learn and what still holds up when they do.

What we test

Local data storage

Whether tokens, credentials, or sensitive data are stored insecurely on the device, cached in plaintext, or written to logs and backups where they can be recovered.

Network and transport security

TLS usage, certificate validation and pinning, and whether traffic can be intercepted or manipulated by an attacker positioned between the app and the server.

API backend authorization

Direct testing of the backend the app relies on, bypassing the app entirely, for broken object-level and function-level authorization and excessive data exposure.

Code and client-side controls

Hardcoded secrets, exposed endpoints, and the resilience of client-side protections against reverse engineering and tampering.

The report you receive

The report covers both the app and its backend. It contains:

  • An executive summary covering device-side and server-side risk.
  • A methodology statement referencing the OWASP Mobile Application Security standards and the OWASP API Security Top 10.
  • Findings rated by severity with reproduction steps, impact, and remediation.
  • Separate treatment of client-side and backend findings, so fixes land in the right place.
  • A retest and updated report once remediation is complete.

Findings we commonly report in this category

Hardcoded secrets in the binary

API keys or credentials embedded in the app and recoverable by anyone who decompiles it.

Insecure local storage

Tokens or sensitive data cached in plaintext on the device, readable if the device is lost, jailbroken, or compromised.

Backend authorization bypass

The API trusting the app and failing to enforce authorization when called directly, exposing data to anyone who skips the app.

Weak certificate validation

Missing or bypassable certificate pinning that allows an attacker to intercept and read the app's traffic.

Frequently asked questions

Do you test the app, the backend API, or both?

Both, and it matters. Many of the most serious mobile findings live in the API, because an attacker bypasses the app and calls the backend directly. Testing only the app while ignoring its server leaves the biggest risks unexamined.

Do you need our source code?

Not necessarily. We can test the compiled app as an attacker would, and source access can make certain checks faster and deeper. We agree the approach during scoping based on what gives you the most value.

Which standard do you follow?

The OWASP Mobile Application Security Verification Standard and Testing Guide for the app, and the OWASP API Security Top 10 for the backend, so the report references recognized methodologies.

How long does a mobile app test take?

Typically one to two weeks per platform depending on the app's size and the backend's complexity. We confirm the exact scope and timeline in a short call.

Related services

Ready to scope your mobile app penetration testing?

Book a free 30-minute scoping call. We agree the scope, timeline, and a fixed price up front — no obligation, and no surprises for your deadline.