Mobile app security testing is process of finding vulnerabilities in how your app handles data, authenticates users, communicates over networks, and protects its own code from tampering. It's separate from functional testing (does feature work?) and performance testing (does it work fast?). Security testing asks: can someone exploit this?
The OWASP Mobile Application Security Verification Standard (MASVS) defines baseline. It covers data storage, cryptography, authentication, network communication, platform interaction, code quality, and resilience. Most teams know OWASP exists. Fewer actually test against it.
In this we covers 7 specific vulnerabilities, each with a practical "test this now" step you can run on your app today. No abstract categories. No 50-item checklists. Seven concrete things to check, tool that checks them, and what happens if you don't.
1. Insecure data storage
The vulnerability: Sensitive data (user credentials, payment tokens, personal information) stored in plaintext on device. On Android, this means SharedPreferences or SQLite databases without encryption. On iOS, this means NSUserDefaults or plist files instead of Keychain.
Test it now: On a rooted Android device or emulator, navigate to /data/data/<package_name>/shared_prefs/ and open XML files. If you can read passwords, API tokens, or session IDs in plaintext, that's a failure. On iOS, use a tool like iMazing to extract app's data container and check for sensitive values stored outside Keychain.
What happens if you skip it: A user on a rooted device (or a device with malware that has storage access) can read your app's stored credentials and impersonate user. In fintech and healthcare apps, this is a compliance violation under PCI-DSS and HIPAA.
Tool: MobSF (Mobile Security Framework), open-source, does automated static and dynamic analysis for both Android and iOS.
2. Insecure network communication
The vulnerability: API calls sent over HTTP instead of HTTPS, or HTTPS implemented without proper certificate validation. Man-in-the-middle (MITM) attacks can intercept data in transit if app doesn't verify server's certificate or allows self-signed certificates.
Test it now: Set up a proxy (Charles Proxy or Burp Suite) between device and your API server. If you can see full API request and response (including auth tokens and user data) in proxy without any warnings or errors from app, app isn't pinning certificates. Try replacing server's certificate with a self-signed one. If app still connects, that's a failure.
What happens if you skip it: An attacker on same Wi-Fi network (coffee shop, airport, hotel) can intercept every API call, including login credentials and payment information. OWASP MASVS lists this as MASVS-NETWORK-1.
Tool: Burp Suite Community Edition (free) for MITM proxy testing.
3. Weak authentication and session management
The vulnerability: The app accepts weak passwords, doesn't enforce account lockout after failed attempts, uses long-lived session tokens that never expire, or stores session tokens insecurely.
Test it now: Try logging in with password "123456." If app accepts it, password strength enforcement is missing. Log in, copy session token from API response (using a proxy), then log out. Try using old session token to make an API call. If it still works, session invalidation on logout is broken. Wait 24 hours without using app and check if session is still active. If it is, session timeout is missing.
What happens if you skip it: An attacker who steals a session token (via insecure storage or network interception) can access user's account indefinitely. No expiration, no lockout, no re-authentication.
Tool: Burp Suite (for session token inspection), manual test cases for login security (account lockout, password strength).
4. Code tampering and reverse engineering
The vulnerability: The app's binary (APK or IPA) can be decompiled, modified, and redistributed. An attacker can extract API keys, modify payment logic, bypass license checks, or inject malicious code.
Test it now: Download your own APK and run it through JADX (Android decompiler). If you can read your source code, find hardcoded API keys, and see your backend URLs in plaintext, app lacks obfuscation. For iOS, use Hopper to disassemble IPA and check if class names and method names reveal business logic.
What happens if you skip it: Attackers create modified versions of your app (with ads injected, premium features unlocked, or payment flows bypassed) and distribute them on third-party app stores. In gaming and subscription apps, this is a direct revenue loss.
Mitigation: Use ProGuard or R8 on Android and Bitcode on iOS for code obfuscation. Implement runtime integrity checks that detect if app binary has been modified.
5. Excessive app permissions
The vulnerability: The app requests permissions it doesn't need (camera when there's no camera feature, contacts when there's no contact import, location when there's no location-based functionality). Each unnecessary permission increases attack surface.
Test it now: On Android, go to Settings > Apps > [Your App] > Permissions. List every permission app has. For each one, ask: "Does app have a feature that uses this?" If not, permission is excessive. On iOS, check app's Info.plist for permission usage descriptions (NSCameraUsageDescription, NSLocationWhenInUseUsageDescription) and verify each one maps to an actual feature.
What happens if you skip it: Google Play and App Store increasingly flag and reject apps with excessive permissions. Users see permission requests and decide whether to trust app. Requesting unnecessary permissions erodes trust and can trigger app store review rejections.
Tool: Manual review of AndroidManifest.xml (Android) and Info.plist (iOS). MobSF flags excessive permissions automatically.
6. Insecure third-party SDKs
The vulnerability: Your app includes analytics SDKs, ad networks, push notification services, and payment libraries from third parties. Each one has access to your app's data and network. A vulnerability in a third-party SDK is a vulnerability in your app.
Test it now: List every third-party dependency in your app (check build.gradle for Android, Podfile for iOS, package.json for React Native). Cross-reference each one against known vulnerability databases: Snyk for npm packages, OWASP Dependency-Check for Java/Android, and GitHub Dependabot for automated alerts.
What happens if you skip it: A known vulnerability in an older version of a payment SDK or analytics library can be exploited without touching your code. CircleCI's security guide notes that "attackers often target vulnerabilities within software supply chain rather than directly assaulting app's main code."
Tool: Snyk (free tier available), GitHub Dependabot (free), OWASP Dependency-Check (open-source).
7. Improper platform interaction
The vulnerability: The app exposes internal components (Activities, Content Providers, Broadcast Receivers on Android; URL schemes and Universal Links on iOS) that external apps can invoke without authorization. An attacker can craft an intent or URL that triggers a sensitive action in your app.
Test it now: On Android, check your AndroidManifest.xml for exported components (android:exported="true"). For each exported Activity, Service, or Content Provider, verify that it requires authentication or permission before executing. Use adb to send an intent directly to an exported component and check if it executes without requiring user to be logged in.
What happens if you skip it: A malicious app on same device can invoke your app's internal actions. If a Content Provider exposes user data without authentication, any app on device can read it. If a deep link handler doesn't validate URL, an attacker can craft a URL that bypasses authentication or triggers a payment.
Tool: Drozer (Android, open-source) for testing exported components. Manual review of AndroidManifest.xml and iOS URL scheme handlers.
How security testing fits alongside functional testing
Security testing and functional testing are separate but complementary. Functional testing asks "does login work?" Security testing asks "can someone bypass login?" You need both.
The practical integration point is your CI/CD pipeline. Functional tests (smoke, regression) run on every build. Security scans (SAST with MobSF, dependency checks with Snyk) also run on every build, in parallel. If either fails, build is blocked.
Drizz handles functional layer: plain-English tests run on real devices to validate that login, checkout, and payment flows work correctly across device matrix. Security testing tools (MobSF, Burp Suite, Snyk) run alongside to validate that those same flows are secure. The combination ensures feature works AND that it's safe.
For teams in fintech, healthcare, and regulated industries, Drizz supports on-prem and VPC deployments where all test data stays within your network. SSO/SAML, RBAC, audit logs, and encrypted storage are available for enterprise security teams.
For a full breakdown of all testing types including how security testing relates to functional, performance, and compatibility testing, see our types guide.
FAQ
What is mobile app security testing?
It's process of finding vulnerabilities in how your app stores data, communicates over networks, authenticates users, and protects its code. It identifies weaknesses that attackers could exploit to steal data or compromise app.
What is OWASP MASVS?
The Mobile Application Security Verification Standard, published by OWASP. It defines security requirements across data storage, cryptography, authentication, network communication, platform interaction, code quality, and resilience. It's industry baseline for mobile security testing.
What tools are used for mobile app security testing?
MobSF (static + dynamic analysis, open-source), Burp Suite (network interception and MITM testing), Snyk (dependency vulnerability scanning), JADX (Android decompilation), Drozer (Android component testing), and NowSecure (enterprise automated MAST).
How often should mobile security testing be done?
SAST and dependency scans should run on every build in CI/CD. Manual penetration testing and dynamic analysis should happen before every major release and after any security-related code change (authentication updates, new third-party SDK integrations).
Can functional testing catch security issues?
Sometimes, indirectly. A functional test that validates login lockout after 5 failed attempts is also a security test. But dedicated security testing (MITM interception, code decompilation, permission auditing) catches vulnerabilities that functional tests can't reach.
Is mobile security testing different from web security testing?
Yes. Mobile adds: insecure local data storage (SharedPreferences, Keychain), code tampering and reverse engineering (APK decompilation), excessive app permissions, OEM-specific security behavior, and platform interaction vulnerabilities (exported components, deep link handlers).
