Android WebView Exploitation: A Bug Bounty Perspective

I've been reverse-engineering Android APKs since class 10. What started as curiosity about how apps work turned into a systematic approach to finding vulnerabilities in production applications.

This post covers the attack surfaces I look for in Android WebView implementations — the kind of misconfigurations that earn bug bounty payouts.

Why WebViews?

Android WebViews are embedded browsers. They load web content inside native apps. And developers consistently misconfigure them because:

1. The defaults are insecure — JavaScript is disabled by default, but every app enables it
2. Bridge functions expose native capabilities — addJavascriptInterface is basically an RCE surface
3. URL validation is hard — Deep links and intent filters create navigation bypasses

The Methodology

My approach to WebView auditing follows a consistent pattern:

APK Acquisition → jadx Decompilation → Manifest Analysis → 
WebView Configuration Audit → JavaScript Bridge Enumeration → 
Attack Surface Mapping → Exploitation → Report

Step 1: Find the WebViews

After decompiling with jadx, I grep for WebView instantiation:

// Patterns to search for
WebView
loadUrl(
addJavascriptInterface
setJavaScriptEnabled(true)
WebViewClient
shouldOverrideUrlLoading

Step 2: Check the Configuration

The critical settings:

// Dangerous configurations
webView.getSettings().setJavaScriptEnabled(true);     // Required but risky
webView.getSettings().setAllowFileAccess(true);        // File system access
webView.getSettings().setAllowUniversalAccessFromFileURLs(true); // SOP bypass
webView.addJavascriptInterface(bridge, "Android");     // Native bridge

Step 3: Map the Bridges

JavaScript bridges are the highest-value targets. If addJavascriptInterface exposes methods that:

• Read device data
• Access authentication tokens
• Modify app state
• Execute system commands

...you have a finding.

Responsible Disclosure

Every vulnerability I find goes through the proper channels — HackerOne for programs that use it, direct security contacts otherwise. The goal isn't exploitation — it's making apps safer for the millions of people who use them.

4 reports submitted. 4 platforms made more secure. The work continues.

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I write about security research, AI systems, and building software that matters. More posts coming.