Notification-Action / Trampoline Authorization Bypass

← Improper Platform Usage

notification_action_authorization_bypass   MEDIUM

Description

A notification action fires a PendingIntent (or, on Android, trampolines through an exported receiver -> activity) that performs a privileged operation - approve transaction, unlock, delete, change account - WITHOUT a fresh authentication decision, because the intermediate component has weaker authorization semantics than the equivalent in-app UI flow. The action surface becomes an unauthenticated entry point into a sensitive operation. The secure path re-authenticates destructive actions and routes them through an authorization check regardless of entry surface (Android/iOS notification-action class).

How it works

A notification action fires a PendingIntent (on Android trampolining an exported receiver to an activity; on iOS a UNNotificationAction) that performs a privileged operation, approve transfer, unlock, or delete, without a fresh authentication decision. The intermediate component has weaker authorization than the equivalent in-app UI: it simply trusts that the notification originated the request, so the notification action becomes an unauthenticated entry point. The secure path routes every entry surface through the same authorization check and re-authenticates destructive actions, so the transfer is refused until the user authenticates.

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 emulator/simulator you control. The demo needs no external tooling; for the optional on-device reproduction the relevant tools are: adb, jadx · iOS: ipsw, Hopper.
2. Locate the target. From the home index, open Notification-Action / Trampoline Authorization Bypass (notification_action_authorization_bypass). 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
• jadx

iOS

• ipsw
• Hopper

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 notification action

Real-world references

Concrete public disclosures that match this vulnerability class:

• Android notification trampolines + iOS UNNotificationAction authorization