Table of contents
- Tools You’ll Need:
- Step-by-Step Process:
- 1. Install Fiddler Classic
- 2. Set Up Memu Player
- 3. Check Memu Player’s Architecture
- 4. Download the Appropriate Frida-Server
- 5. Push Frida-Server to Memu Player
- 6. Grant Permissions to Frida-Server
- 7. Launch Frida on the Emulator
- 8. Verify Frida is Running
- 9. Configure Fiddler to Intercept Traffic
- 10. Bypass SSL Pinning with Frida
- 11. Analyze the Captured Traffic
- 12. Troubleshooting Tips
- Closing Thoughts
In this article, I’ll walk you through how I reverse engineered Instagram to analyze its app traffic. This guide is intended for educational purposes only and not to violate any policies or terms of service. Reverse engineering can provide insights into app behaviors, network requests, and underlying mechanisms, but it should always be conducted ethically.
Tools You’ll Need:
Fiddler Classic by Telerik: A powerful web debugging proxy that captures HTTP/HTTPS traffic.
Memu Player: An Android emulator for running the Instagram app.
Frida: A dynamic instrumentation toolkit for analyzing and modifying apps.
Step-by-Step Process:
1. Install Fiddler Classic
Start by downloading and installing Fiddler Classic from Telerik’s official website. Fiddler allows you to intercept and analyze HTTP and HTTPS traffic. During installation, ensure that HTTPS decryption is enabled in Fiddler’s settings to view encrypted traffic.
2. Set Up Memu Player
Memu Player is a lightweight Android emulator. Install it on your PC and configure it as your test environment for running Instagram. Memu Player is preferred for its simplicity and compatibility with tools like ADB and Frida.
3. Check Memu Player’s Architecture
Before proceeding, you need to identify the CPU architecture of Memu Player to ensure compatibility with Frida. Use the following ADB command:
adb shell getprop ro.product.cpu.abi
This command will return the CPU architecture, such as armeabi-v7a, arm64-v8a, or x86.
4. Download the Appropriate Frida-Server
Visit Frida’s official GitHub releases page and download the latest frida-server build corresponding to the CPU architecture identified in the previous step. Ensure you download the correct version to avoid compatibility issues.
5. Push Frida-Server to Memu Player
Once downloaded, rename the file to frida-server for simplicity. Use the following command to push the file to the emulator:
adb push frida-server /data/local/tmp/
This places the frida-server file in the temporary directory of the emulator.
6. Grant Permissions to Frida-Server
For the Frida server to run correctly, grant it execute permissions with the following command:
adb shell "chmod 777 /data/local/tmp/frida-server"
This step ensures the server can execute without restrictions.
7. Launch Frida on the Emulator
Start the Frida server on Memu Player using this command:
adb shell "/data/local/tmp/frida-server &"
The & at the end runs the server in the background, allowing you to continue with other tasks.
8. Verify Frida is Running
To confirm that the Frida server is operational, list the attached processes using:
frida-ps -U
This command displays all processes currently running on the emulator. If successful, you’ll see a list of active applications.
9. Configure Fiddler to Intercept Traffic
Now, set up Fiddler to capture traffic from the emulator:
Open Fiddler Classic and note your PC’s IP address.
Open Memu Player’s Wi-Fi settings and configure the proxy settings:
Set the proxy IP to your PC’s local IP address.
Set the proxy port to Fiddler’s default port (8888).
Enable “Decrypt HTTPS Traffic” in Fiddler’s settings to intercept encrypted data.
10. Bypass SSL Pinning with Frida
Most modern apps, including Instagram, use SSL pinning to prevent traffic interception. To bypass this, use Frida’s code-sharing feature:
frida --codeshare akabe1/frida-multiple-unpinning -U -f <appname>
Replace <appname> with the package name of the Instagram app (e.g., com.instagram.android). This command:
Injects Frida scripts to disable SSL pinning.
Launches the app while allowing Fiddler to capture traffic.
Once the app starts, you should begin seeing its HTTP/HTTPS requests in Fiddler.
11. Analyze the Captured Traffic
Use Fiddler’s interface to review the captured traffic. Look for API requests, headers, and payloads to understand how the app communicates with its backend servers. This data can reveal valuable insights about app behavior.
12. Troubleshooting Tips
If traffic isn’t appearing in Fiddler, double-check the proxy settings and ensure the emulator is connected to the same network as your PC.
Restart the Frida server if you encounter issues with SSL pinning bypass.
Update your tools (Fiddler, Frida, and Memu Player) to their latest versions to avoid compatibility issues.
Closing Thoughts
Reverse engineering Instagram or any app requires technical expertise, patience, and adherence to ethical guidelines. This process can help you learn about network security, debugging, and app design. However, always respect the legal and ethical boundaries of such activities. Unauthorized reverse engineering or data access could lead to serious consequences.
By following this guide, you’ll gain practical experience in traffic analysis and reverse engineering techniques. Use this knowledge responsibly to further your understanding of app development and security practices.