App-Widget / RemoteViews Action Injection

← Improper Platform Usage

remoteviews_widget_action_injection   HARD

Description

An app-widget builds RemoteViews whose click/action PendingIntent is derived from attacker-influenceable widget-configuration state (config-activity extras, collection-item data), so tapping the widget invokes a privileged in-app action (transfer, unlock, delete) with parameters the attacker chose - external widget state flows into a privileged operation with no re-authorization. The secure path binds only immutable, explicit PendingIntents to fixed actions and re-authenticates destructive operations (Android RemoteViews-action class).

How it works

An app-widget builds RemoteViews whose click PendingIntent is derived from attacker-influenceable widget-config state (config activity extras, collection-item data). Because that external state flows straight into the action and its parameters, tapping the widget invokes a privileged in-app operation (transfer) with an attacker-chosen amount and account and no re-authentication. A mutable or implicit PendingIntent lets the payload be filled in later, turning untrusted widget state into a privileged unauthenticated action. The secure path binds only an immutable, explicit PendingIntent to a fixed safe action and re-authenticates destructive operations, so the attacker extras are ignored.

How to exercise it. DVMA is the harness - open this module from the home index and tap the demo action. The screen ships the malicious input and simulates the attacker (e.g. the companion app, crafted intent, or scanned payload) in-process, and the evidence panel prints the proof. The Tools (optional) and Attack inputs below are only needed to reproduce the exploit end-to-end on a real device.

Exploit steps

1. Set up. Build DVMA with a flavor that enables the Improper Platform Usage category (e.g. --dart-define-from-file=config/flavors/dev.json) and run on an Android emulator you control. The demo needs no external tooling; for the optional on-device reproduction the relevant tools are: adb, drozer, jadx.
2. Locate the target. From the home index, open App-Widget / RemoteViews Action Injection (remoteviews_widget_action_injection). The How it works section above describes this module’s specific weakness; the screen states the intended-secure behavior and exposes the vulnerable action.
3. Exploit. From a co-resident/attacker context (adb shell am start/drozer, or a crafted deep link / QR), send the untrusted input to the exported component or WebView and confirm the app performs the unsafe action (navigation, JS execution, file/URI access) with no validation.
4. Observe the evidence. Trigger the vulnerable action and read the evidence panel - it prints the concrete proof (leaked value, accepted replay, executed payload, or unauthorized result).
5. Contrast with the secure path. Run the module’s secure/hardened action (where provided) and confirm the same attack is rejected - this is what a correct implementation should do.
6. Map it back. Cross-reference the MASTG v2 test(s) MASTG-TEST-0381 for the canonical procedure and remediation.

Tools (optional)

• adb
• drozer
• jadx

Attack inputs

Payloads/artifacts you author for the on-device attack. The demo already ships and simulates these in-process (e.g. the malicious companion app / crafted intent is emulated inside the screen), so you only need to craft them to reproduce the exploit on a real device:

• crafted widget-config extras

Real-world references

Concrete public disclosures that match this vulnerability class:

• Android App Widgets / RemoteViews and PendingIntent actions