PTS2025

Apkpatcher: Reverse Engineering and Modifying Android Applications Without Rooting
2025-07-03, 14:00–16:30 (Europe/Paris), Room LW109

This hands-on workshop will guide participants through the process of reverse engineering and modifying Android applications without the need for rooted devices.
I will present apkpatcher to explore various techniques to analyze, modify, and remove tracker on Android apps, focusing on practical skills that can be applied in real-world scenarios.

Objectives

Understand the fundamentals of reverse engineering Android applications.
Learn to use debugging tools to analyze Android app behavior.
Bypass security mechanisms using Frida scripts.
Sniff and replay Bluetooth Low Energy (BLE) communications.
Modify Smali code to alter app functionality.
Reverse engineer native libraries used in Android apps.
Perform Man-in-the-Middle (MITM) attacks on HTTPS services.

Workshop Outline

  1. Introduction to Android Reverse Engineering
    - Overview of Android app architecture.
    - Setting up the environment for reverse engineering.
  2. Using a Debugger on Android Applications
    - Introduction to Android debugging tools.
    - Practical exercise: Debugging an Android app.
  3. Bypassing Security with Frida
    - Introduction to Frida and its capabilities.
    - Writing Frida scripts to bypass security checks.
    - Hands-on: Implementing a Frida script.
  4. Sniffing and Replaying BLE Communications
    - Overview of BLE technology.
    - Tools for sniffing BLE traffic.
    - Practical exercise: Capturing and replaying BLE data.
  5. Modifying Smali Code
    - Introduction to Smali and its role in Android apps.
    - Techniques for modifying Smali code.
    - Hands-on: Altering app functionality through Smali.
  6. Reverse Engineering Native Libraries
    - Understanding native libraries in Android.
    - Tools and techniques for reverse engineering.
    - Practical exercise: Analyzing a native library.
  7. MITM on HTTPS Services
    - Introduction to MITM attacks.
    - Setting up a MITM proxy for HTTPS.
    - Hands-on: Intercepting and modifying HTTPS traffic.

Prerequisites

Familiarity with command-line tools.
Laptop and Android phone

Expected Outcomes

By the end of the workshop, participants will have gained practical experience in reverse engineering and modifying Android applications. They will be equipped with the skills to analyze app security and implement modifications without requiring rooted devices.

Workshop Duration: 1.5 hours
Benoit Forgette

Passionate about how systems work since my childhood and with an initial education in computer science, I gradually moved to the security of these systems and the electronic part of these equipments.Today, I work as a Cybersecurity Engineer in software and hardware reverse engineering at Quarkslab, where my daily work consists in disassembling equipments sent by our clients, then inspecting all their attack surfaces (hardware, radio, software, cloud). Then, we help our clients to find the best way to protect their systems and their equipments.

In this work, the part that seems to me the most interesting is the automation/instrumentation/hijacking part. It is fascinating to see how much it is possible to hijack a piece of equipment from its original purpose. This is even more impressive when we talk about physical equipment which has an impact on its environment.