CyberCode Academy

Course 5 - Full Mobile Hacking | Episode 5: Exploiting Insecure Storage and Access Controls via Reverse Engineering and ADB

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In this lesson, you’ll learn about:
  • Access control flaws & exposed debug interfaces: how application components and debug/logging channels can unintentionally reveal sensitive functionality or credentials when accessible from outside the normal UI (e.g., via dev/debug interfaces), and why minimizing exposed surfaces is critical.
  • Log‑based information leakage: why verbose runtime logs (debug logs, stack traces, or logcat output) can leak API credentials or internal activity flows and how logging policies should avoid emitting secrets.
  • Input validation failures enabling file access: the risk when inputs meant for URLs or safe IDs are not validated and are instead used directly to read files or resources—leading to unauthorized access to internal app files or external storage.
  • Reverse‑engineering for source‑level discovery (conceptual): how attackers analyze an app’s distributed package to inspect code paths, SQL queries, and hardcoded secrets; why attackers look for hardcoded credentials, embedded query strings, and sensitive constants in decompiled artifacts. (Discussed at a high level — use only approved analysis tools in controlled labs.)
  • Insecure storage patterns & common pitfalls: typical insecure storage locations and formats that leak secrets:
    • Shared Preferences / XML files: plaintext credentials stored in app-config XMLs.
    • SQLite databases: sensitive tables and records stored without encryption.
    • Temporary files: transient files (temp dumps) that retain secrets on disk.
    • External storage (SD card): writable, world‑readable areas where sensitive data may be exposed to other apps or users.
  • Attack surface demonstrated (high level): combining exposed components, poor input validation, and insecure storage enables an attacker to bypass intended UI controls and access stored credentials or private data — a clear example of failing the “defense in depth” principle.
  • Mitigations & secure design recommendations:
    • Never store credentials or secrets in plaintext; use platform keystores or strong encryption.
    • Validate and strictly sanitize all user‑supplied input before using it in file access or resource locators.
    • Avoid writing sensitive data to external/shared storage; prefer protected internal storage with proper file permissions.
    • Minimize and sanitize logging (do not log secrets or sensitive fields).
    • Harden app components: restrict component exposure, remove debug hooks from production builds, and enforce proper access checks on exported activities/services.
    • Secure databases with encryption-at-rest and limit sensitive columns; avoid temporary files for secret data.
  • Defensive testing & lab guidance:
    • Teach these issues using intentionally vulnerable apps (like DVAR) inside isolated, authorized lab environments only.
    • Instructors should provide sanitized sample APKs and datasets; students must never attempt these techniques against live/production apps or devices without explicit authorization.
    • Emphasize documentation: record findings, reproduce safely, and communicate issues with clear remediation steps for developers.
  • Core takeaway:
    Effective mobile app security requires careful control of exposed interfaces, strict input validation, and secure handling of all sensitive data (no plaintext secrets, no sensitive external storage). Combining secure coding practices with careful logging, testing, and least‑privilege design prevents the kinds of data exposures highlighted by the DVAR case study.


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CyberCode AcademyBy CyberCode Academy