Mobile Application Security Testing Guide (MASTG)

What MASTG Is and What It Is For

MASTG is an OWASP testing guide for mobile applications, so its purpose is to make mobile security assessment repeatable rather than ad hoc. It gives testers, developers, and assessors a shared vocabulary for what to verify, what evidence to collect, and how to structure findings across Android and iOS.

That matters because mobile apps do not fail only through obvious coding flaws. They also fail through platform misconfiguration, weak client-side protections, insecure storage, broken trust assumptions, and testing blind spots that informal review often misses.

How MASTG Structures Mobile Security Testing

MASTG is best understood as a methodology, not just a checklist. It helps teams organise testing around the app lifecycle and the platform surfaces that matter most: code, configuration, runtime behaviour, local data handling, network communication, and integration points with device services and backend APIs.

That structure is useful because mobile testing needs both static and dynamic perspectives. Some weaknesses are visible in the binary, manifest, or packaging choices, while others only emerge when the app runs on a device or emulator and interacts with storage, sensors, attestation, or remote services.

For teams that also need a broader appsec baseline, OWASP ASVS gives a complementary verification model for authentication, access control, and validation, while MASTG adapts the testing lens to mobile-specific conditions.

Core Weaknesses MASTG Helps Find

MASTG is especially valuable where mobile security failures are easy to underestimate. Common examples include hard-coded secrets, weak certificate validation, insecure local storage, exposed debug features, excessive permissions, and broken authentication flows that are safer in theory than they are on the handset.

It also helps testers look beyond the app package itself. Mobile risk often sits in the relationship between app, device, operating system, and backend, so a test that ignores jailbreak or root conditions, transport trust, or attestation evidence can miss the actual attack path.

At the programme level, MASTG works well with an application-security testing approach such as Application Security Guide, because both emphasise repeatable testing methods, evidence quality, and the difference between scanning and real assurance. For mobile-specific offensive and defensive coverage, Mobile App Security Guide and OWASP Mobile Top 10 Guide provide the risk context that MASTG then turns into testable checks.

How MASTG Fits Into Mobile App Assurance

MASTG is most effective when it is used as part of an assurance workflow, not as a one-time audit artifact. Security teams can use it to define test scope, developers can use it to understand what evidence a reviewer will expect, and assessors can use it to make reports more consistent across releases and vendors.

Its practical value is that it creates a bridge between build-time security and runtime validation. A mobile app may pass code review yet still fail in a real device state, under a different network condition, or when an attacker manipulates storage, hooks methods, or tampers with the client environment.

For teams that test those runtime behaviours directly, the Mobile App Security Testing Guide is the natural operational companion to MASTG, because it covers the same testing discipline with mobile-specific techniques such as certificate pinning recovery, app attestation, and runtime analysis. Where the supply chain matters to the app’s trust model, the OWASP Mobile Top 10 M2 Inadequate Supply Chain Security Guide helps extend that assurance into SDKs, signing, and build provenance.

Practitioner Guidance

Why practitioners should care: MASTG is useful when teams need more than generic mobile hardening advice. It gives assessors a repeatable way to prove whether a mobile app’s security claims hold up under real testing, rather than assuming the presence of controls means those controls actually work.

What to watch for: The most common mistake is treating mobile testing as a shallow layer over web app testing. Mobile-specific risks often sit in platform behaviour, local trust stores, package signing, runtime tampering, and device state, so the test plan should explicitly reflect those conditions.

Practitioner takeaway: Use MASTG as the evidence-backed test method, then map the findings into your broader appsec and mobile risk programme so the results drive remediation, not just reporting.

Related resources from NHI Mgmt Group

• Mobile Application Security Testing
• Mobile Application Security
• Application security testing
• Security Testing