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Why mobile requires a different testing approach
Testing a mobile application is fundamentally different from testing a web app. While web app penetration testing focuses on server-side logic and browser vulnerabilities, mobile pentesting introduces the device itself as a hostile environment. Attackers have physical control over the device, root/jailbreak access, and the ability to manipulate the runtime environment.
Local storage
Mobile apps often store sensitive data (tokens, PII, transaction history) on the device. Testing verifies that data is encrypted using Keystore/Keychain and not exposed in plain text to other apps.
Binary protections
Decompiling an Android APK or iOS IPA is trivial. Testing evaluates the effectiveness of code obfuscation, anti-tampering mechanisms, and environmental checks (root/jailbreak detection).
Network communication
Beyond standard TLS, mobile apps must employ certificate pinning to prevent Man-in-the-Middle (MitM) attacks, ensuring the app only talks to authorized servers.
Critical attack surfaces for fintech apps
Certificate pinning bypass
If an app doesn't implement certificate pinning, an attacker on the same network can intercept API traffic by installing a malicious root certificate. If pinning is implemented poorly, tools like Frida can be used to hook into the runtime and bypass the checks entirely. A thorough pentest attempts to bypass these controls to assess network security.
Biometric authentication bypass
Relying solely on local biometric checks (FaceID/TouchID) without cryptographic binding to a server-side session allows attackers with device control to force a successful authentication response. We test the implementation of biometric APIs to ensure they are resistant to local bypass.
Prepare the build and backend together
Send the exact Android or iOS build planned for release, test accounts for each role, API base URLs, deep links, certificate pinning details, push notification paths, and a list of third-party SDKs. State whether the build points to staging or production.
Mobile risk crosses the app and server. Local storage, logs, screenshots, exported components, deep links, and runtime controls sit on the device. Ownership, transaction state, rate limits, and protected data must still be enforced by the backend.
Decide what the report must prove
For launch approval, test the release build and critical user paths. For a customer or audit request, include the covered app version, API scope, method, dates, findings, and retest status. For a major redesign, review architecture before the final build so the team can change trust boundaries without rework.
Need your iOS or Android fintech app tested against real-world attack scenarios?
Book a Mobile PentestInter-Process Communication (IPC) and deep links
Apps interact with other apps via intents (Android) and deep links/custom URL schemes (iOS). Insecurely exported activities or misconfigured deep link handlers can allow malicious apps on the same device to trigger unintended actions, bypass authentication, or extract sensitive data.
The OWASP Mobile Application Security Verification Standard (MASVS)
A credible mobile pentest should align with the OWASP MASVS, the industry standard for mobile security. For Nigerian fintechs, we recommend targeting MASVS-L2 (Defense-in-Depth) combined with MASVS-R (Resiliency against reverse engineering and tampering).
- Architecture, Design and Threat Modeling Requirements: Validating security controls early in the SDLC.
- Data Storage and Privacy: Ensuring no sensitive data is leaked locally.
- Cryptography: Verifying proper use of established cryptographic libraries.
- Authentication and Session Management: Securing local and remote sessions.
- Network Communication: Enforcing secure transport and pinning.
- Platform Interaction: Securing IPC, deep links, and permissions.
- Code Quality and Build Setting: Hardening the binary.
The cost of hardcoded keys
During a recent assessment of a Nigerian mobile money app, we extracted the compiled APK, decompiled it, and found hardcoded AWS credentials in a utility class. This allowed direct access to an S3 bucket containing user KYC documents. The API was secure, but the mobile binary compromised the entire platform.
Related reading
Guides: Web App Penetration Testing · How to Book a Pentest
Services: Mobile App Penetration Testing · API Security Testing
Industries: Mobile Money · Digital Banking
Frequently asked questions
How does mobile pentesting differ from web pentesting?
Mobile pentesting involves analyzing compiled binaries, local device storage, IPC mechanisms, and certificate pinning, whereas web pentesting focuses primarily on server-side APIs and browser-based client security.
Do we need a mobile pentest if our APIs are already tested?
Yes. Even if your APIs are secure, a mobile app can expose vulnerabilities through insecure local storage, improper biometric authentication implementation, or hardcoded API keys.
What is certificate pinning and why is it important?
Certificate pinning ensures your app only communicates with a specific server certificate, preventing Man-in-the-Middle (MitM) attacks even if the device trusts a malicious root CA.