Mobile and web apps share the same server-side risks: weak authorization, bad input handling, vulnerable dependencies. They differ in where the code runs, how it is updated and what an attacker can see. A mobile app is a program installed on a device the user controls, so more depends on what the client does and does not hold.
Where they overlap
Both talk to APIs, both need authentication and authorization enforced on the server, and both use third-party code. The OWASP mobile cheat sheet says to treat all networks as untrusted, use HTTPS everywhere and validate input. Those would fit a web checklist as well. If your backend is weak, neither client fixes it.
Where they differ
Code delivery and updates. A web app updates when you deploy. A mobile app updates when the user installs a new version, after app store review. That is why MASVS includes controls for an up-to-date platform (CODE-1) and a mechanism to enforce app updates (CODE-2). On the web you rarely need that.
What the attacker can inspect. Web code is delivered to the browser, so it is always visible. A mobile app is a binary on the user's device, and a determined attacker can reverse and modify it. MASVS has a whole group, RESILIENCE, for this, covering platform integrity, anti-tampering and resistance to static and dynamic analysis. Web apps do not have an equivalent group.
Local storage and secrets. A browser offers cookies and web storage with the same-origin model. Mobile offers private app storage, shared folders, backups and a hardware-backed keystore. MASVS-STORAGE splits storing sensitive data securely from preventing accidental leaks through backups and logs.
Platform entry points. Mobile apps expose inter-process communication, deep links and WebViews, and show data through screenshots and notifications. MASVS-PLATFORM covers IPC, WebViews and the user interface. The web has its own set (cross-origin rules, redirects, frames) that mobile does not share in the same way.
Local authentication. Mobile apps commonly use biometrics or a device PIN (MASVS-AUTH-2). Browsers have passkeys and password managers, which are a different model.
Network trust. Mobile apps can pin identity for the endpoints under the developer's control (MASVS-NETWORK-2), instead of trusting every default root CA.
Privacy surface. Mobile apps often carry multiple third-party SDKs that run with the app's permissions, which is why MASVS-PRIVACY discusses SDK consent in detail.
What to test where
- Server authorization. Web: Yes. Mobile: Yes.
- Input validation on the server. Web: Yes. Mobile: Yes.
- Client-side storage review. Web: Cookies, web storage. Mobile: Keystore, files, backups, logs.
- Update strategy. Web: Deploy. Mobile: Version gate.
- Tamper resistance. Web: Rarely. Mobile: Decide per app.
- Third-party code. Web: Scripts, packages. Mobile: SDKs, libraries.
How to split the effort
Start with the backend, since both clients depend on it. Then review the client that your users actually run. If you ship both, do not assume a review of one covers the other: Android and iOS also differ from each other, and the MASTG keeps their tests separate.
For a useful companion on the server side, see why client checks must be repeated on the server.
Quick check
Do I need a different team for mobile security?
Not necessarily, but someone needs the platform knowledge for storage, keystores, WebViews and updates. The backend skills carry over directly.
Is a progressive web app a mobile app for these purposes?
It runs in the browser model, so web guidance applies. Check the specific features you use.
Sources
Last reviewed: 19 October 2026.
