Overview

An implicit intent is an Intent that does not name a concrete target component. Instead, it declares an action, and optionally data or categories, and Android resolves it to an installed component with a matching <intent-filter>. See MASTG-KNOW-0025 for background on explicit and implicit intents and intent resolution.

Android apps commonly use implicit intents with extras when they intentionally delegate data to another app selected by the system or the user. Typical legitimate uses include sharing user-selected content with ACTION_SEND, attaching metadata for an external viewer, or launching a chooser when the user decides which app receives the data.

The issue appears when the app attaches sensitive or security-relevant extras to an implicit intent without constraining the recipient. During intent resolution, any installed app with a matching <intent-filter> can become the selected recipient and receive the full extras Bundle. This can disclose credentials, session tokens, one-time codes, personal data, account identifiers, or internal state to an untrusted app. Depending on the data, the impact can include privacy leakage, session compromise, account takeover, or unauthorized use of backend APIs.

This test checks whether the app creates and dispatches implicit intents that carry sensitive extras. Relevant patterns include creating an Intent with an action, adding extras with putExtra, putExtras, replaceExtras, or a Bundle, and dispatching it through APIs such as startActivity, startActivityForResult, ActivityResultLauncher.launch, startService, bindService, sendBroadcast, or related APIs.

Steps

  1. Use MASTG-TECH-0013 to reverse engineer the app.
  2. Use MASTG-TECH-0014 to look for the relevant APIs.

Observation

The output should contain Intent creation and dispatch sites where extras are added or propagated. For each reported dispatch, the output should include, when available:

Evaluation

The test case fails if an implicit intent carries sensitive or security-relevant extras and another app can declare or register a matching component to receive them.

Further Validation Required:

Inspect each reported code location using MASTG-TECH-0023:

Gekoppelde issues

Koppelingen
is related to MASTG-BEST-0056 Use Explicit Intents for Internal IPC (Android)