Android Intent SecuritySAFE

An agent skill published by android.

The instruction file, verbatim from the audited commit — this is the text the model reads, and the surface the audit's instruction layer examines. Quoted here so you can judge it without cloning anything.

---
name: android-intent-security
description: Best practices for Android Intent security. Use this skill when auditing
  component configurations in AndroidManifest.xml activities, services, receivers)
  or source code handling incoming Intents (getIntent, getParcelableExtra) to prevent
  Intent Redirection and unauthorized access.
license: Complete terms in LICENSE.txt
metadata:
  author: Google LLC
  last-updated: '2026-09-25'
  keywords:
  - recipe
  - Android
  - Security
  - Intent
  - Redirection
  - PendingIntent
  - ContentProvider
  - Service
  - Signature
  - Verification
  - sanitizer
  - Vulnerability
  - Best Practices
---

This skill provides guidelines and patterns to secure Android components
(Activities, Services, Broadcast Receivers, Content Providers) and handle
Intents safely, preventing privilege escalation and unauthorized access.

## Glossary

- **Intent:** An asynchronous messaging object used to request an action from another app component.
- **Exported component:** A component (`android:exported="true"`) that can be launched by other apps on the device.
- **Sticky intent:** A broadcast intent that remains in the system cache after it's sent, allowing any app to retrieve its contents.
- **Signature permission:** A permission whose protection level is set to `signature`, granted only to apps signed with the same developer key.
- **onNewIntent:** An activity lifecycle callback invoked when an activity is launched with `FLAG_ACTIVITY_SINGLE_TOP` and is already running at the top of the history stack.
- **PendingIntent:** A token granted to a foreign application (for example, system services) allowing it to execute a predefined Intent with the creator's permissions.
- **Mutable PendingIntent:** A PendingIntent whose underlying Intent parameters can be modified by the receiving application.
- **ContentProvider:** A component that encapsulates data and provides it to other applications via standard query/insert interfaces.
- **IntentSanitizer:** A utility class in AndroidX Core used to build a safe, sanitized copy of an incoming Intent by filtering out unauthorized components, actions, or extras.
- **Intent redirection (forwarding):** A vulnerability where an application receives an intent from an untrusted source and uses it to launch a private, non-exported component.

## Prerequisites

- The agent **MUST** be able to describe the function and security implications of `onCreate`, `onNewIntent`, and the `singleTop` launch mode.
- The agent **MUST** be able to declare `<activity>`, `<service>`, `<receiver>`, and `<provider>` tags in `AndroidManifest.xml` and define their `android:exported` and `android:permission` attributes.
- The agent **MUST** be able to implement signature verification checks using `PackageManager`.

## Limitations

- This skill focuses on local inter-component and inter-app communication security on the Android platform.
- This skill **doesn't** cover network security, web integration, or host-to-server security.

## Setup and dependencies

- **Android SDK:** Minimum API Level 23 (Android 6.0) is required for standard hardware-backed keystore operations and component validation.
- **AndroidX Core Library:** `androidx.core:core:1.9.0` or higher is **mandatory** to leverage `IntentSanitizer`.
- **Standard API access:** Standard Android `PackageManager` APIs are required for runtime component verification.

*** ** * ** ***

## Intent security logic and decisions

### 1. Intent routing comparison

Evaluate the security features of different intent delivery methods:

| Intent Delivery Method | Scope | Recommended Use Case |
|---|---|---|
| Explicit Intent (Internal) | App Private | Launching internal activities/services |
| Implicit Intent | System Wide | Launching system camera, dialer, or sharing |
| Local Broadcasts (LocalBroadcastManager) (DEPRECATED) | App Private | Internal asynchronous event routing. **Deprecated**: Use in-app observers like Kotlin Flows/SharedFlow, LiveData, or reactive patterns instead. |
| System Broadcasts | System Wide | Receiving system events (NFC, Bluetooth) |

### 2. PendingIntent mutability flag options

Evaluate the security implications of PendingIntent mutability flags:

| Flag Name | Mutability | Recommended Use Case |
|---|---|---|
| `PendingIntent.FLAG_IMMUTABLE` | Immutable | Default for almost all PendingIntents, such as alarms and notifications |
| `PendingIntent.FLAG_MUTABLE` | Mutable | Inline notifications replies, slice actions (requires explicit target intent) |

### 3. Intent handling and redirection logic

IF (the component receives a nested Intent as an extra) {
IF (AndroidX Core 1.9.0+ and higher is available) {
MUST construct an `IntentSanitizer` to explicitly allowlist components, actions, data, and extras.
MUST call `sanitizeByThrowing()` or `sanitizeByFiltering()` before launching.
} ELSE {
MUST verify that the nested Intent's target package matches the current application package.
MUST verify that the target component of the nested Intent is publicly exported.
}
NEVER launch the nested Intent directly without validation.
} ELSE IF (the component handles broadcasts) {
MUST rely on the system's Protected Broadcast mechanism for system events (which guarantees the sender is the system framework).
MUST protect custom receivers with signature-level permissions or use `RECEIVER_NOT_EXPORTED` for dynamic receivers to restrict the sender.
IF (using `ContextCompat.registerReceiver` with `RECEIVER_NOT_EXPORTED` AND `minSdk < 33`) {
MUST verify `<permission android:name="${applicationId}.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION" android:protectionLevel="signature" />` and `<uses-permission android:name="${applicationId}.DYNAMIC_RECEIVER_NOT_EXPORTED_PERMISSION" />` are declared in `AndroidManifest.xml`.
}
}

### 4. PendingIntent security logic

IF (a PendingIntent is created for delivery to another application) {
MUST use `PendingIntent.FLAG_IMMUTABLE` by default.
IF (the PendingIntent must be mutable) {
M

SAFEgrade B · trust 89/100 Nothing in the source contradicts what it says it does. Grade A is reserved for packages that have also passed the behavioural sandbox.

What the source does

Filesystem

none-observed

Network

none-observed

Shell

none-observed

Dependencies

pinned

Secrets in source

none-found

Findings (0)

No findings outside the package's declared scope.

Gates applied: no_behavioural_pass.

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