# Android Legacy Security

> Harden Intent handling, WebView configuration, and FileProvider access in Android apps. Use when securing Intent extras, configuring WebViews, or exposing files via FileProvider; defer manifest export flags and generic Bundle typing to focused Android security guidance.

- Skill: `hoangnguyen0403/android-legacy-security` (Agent Skill, multi-file: 3 files)
- Install (CLI): `npx skillmds@latest add hoangnguyen0403/android-legacy-security`
- Raw SKILL.md: https://api.skillmd.com/api/skills/hoangnguyen0403/android-legacy-security/raw
- Safety review: pending (external: skill-scanner PASS, skillspector PASS)
- Works with: Claude Code, Claude.ai, OpenAI Codex
- Category: Security
- Author: HoangNguyen0403 (https://skillmd.com/u/hoangnguyen0403)
- Updated: 2026-09-09
- Page: https://skillmd.com/skills/hoangnguyen0403/android-legacy-security

---

# Android Legacy Security Standards

## **Priority: P0 (CRITICAL)**

## 1. Secure Intents and Components

- Set `android:exported="false"` for all internal Activities/Services unless needed for deep links.
- Verify `resolveActivity` before starting implicit intents.
- Treat all incoming Intent extras as untrusted — validate all schema/data types.

See [hardening examples](references/implementation.md) for manifest and component restrictions.

## 2. Lock Down WebViews

- Default to `javaScriptEnabled = false`. Use `WebViewClient` and `WebChromeClient` to restrict navigation.
- Disable `allowFileAccess` and `allowFileAccessFromFileURLs` to prevent local file theft via XSS.
- If using `@JavascriptInterface` (API 17+), strictly limit exposed API surface.

See [hardening examples](references/implementation.md) for WebView lockdown patterns.

## 3. Protect Storage and Files

- **NEVER expose `file://` URIs**. Use `FileProvider` to generate `content://` URIs with temporary permissions.
- Use `EncryptedSharedPreferences` for auth tokens and PII. Never use legacy public-read file modes.
- Use `NetworkSecurityConfig` to disable `cleartextTrafficPermitted` and implement certificate pinning.

## Anti-Patterns

- **No Implicit Intents Internally**: Use explicit intents with component class name.
- **No Public Read Modes**: Never expose SharedPreferences or files with global read access.

## References

- [Hardening Examples](references/implementation.md)