Introduction

Modern mobile applications often employ SSL Pinning to prevent Man-in-the-Middle (MitM) attacks. While this is excellent for user security, it poses a significant challenge for legitimate data interoperability and scraping tasks where no public API exists.

In this log, I break down the process of reverse engineering a proprietary real estate app. The goal was to extract accurate pricing data that was not available on their web frontend.

The Toolchain

• Genymotion: Android Emulator (Rooted)
• Burp Suite: Traffic Interception
• Frida: Dynamic Binary Instrumentation
• JADX: APK Decompiler

The Process

The first step involved rooting an Android emulator (Genymotion) and installing the target APK. Simple proxying via Burp Suite failed immediately due to certificate validation errors. The app was hardcoded to trust only its specific server certificate.

Frida Injection

To bypass this, I utilized the Frida instrumentation toolkit. By injecting a JavaScript payload into the runtime process, I was able to hook into the javax.net.ssl.TrustManager class and force it to accept my Burp Suite CA certificate.

Copy
javascript
Java.perform(function (){
    var array_list = Java.use("java.util.ArrayList");
    var ApiClient = Java.use('com.android.org.conscrypt.TrustManagerImpl');
    
    ApiClient.checkServerTrusted.implementation = function(chain, authType){
        // Bypass logic here
        return;
    }
});

Signature Analysis

Once the traffic was decrypted, I discovered the API used a custom signature header generated from the request body and a timestamp. I had to decompile the APK using JADX to find the signing key and replicate the logic in Python.

The result was a robust Python scraper that could generate valid signatures and query the private API directly, bypassing the UI layer entirely and increasing data extraction speed by 400%.