System-Surface -> Privileged App Intent Exposure

← Improper Platform Usage

system_surface_privileged_appintent_exposure   HARD

Description

An App Intent surfaced to many system entry points (Siri, Spotlight, Shortcuts, Widget, Control, Live Activity, Action Button, Apple Intelligence) reaches a privileged operation with no per-surface authorization, so ANY of those externally-invocable surfaces can trigger the action - the surface fan-out widens the attack surface far beyond the app UI (Apple App Intents multi-surface capability-exposure class).

How it works

An App Intent is surfaced to many system entry points (Siri, Spotlight, Shortcuts, Widget, Control, Live Activity, Action Button, Apple Intelligence) and reaches a privileged operation (“export all data”) with no per-surface authorization. A passive, lock-screen-reachable surface such as a Control therefore fires the privileged op with no unlock and no confirmation. This is the surface fan-out problem, distinct from untrusted-parameter authorization. This is an offline, deterministic simulation. The secure path enforces a per-surface allowlist and requires device authentication for sensitive intents.

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 iOS simulator / a device you control. The demo needs no external tooling; for the optional on-device reproduction the relevant tools are: Siri.
2. Locate the target. From the home index, open System-Surface -> Privileged App Intent Exposure (system_surface_privileged_appintent_exposure). 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 an attacker context (a crafted custom-URL-scheme / Universal Link, a malicious document provider / share extension, or a Shortcut), send the untrusted input to the handler and confirm the app performs the unsafe action (navigation, file/URL access, privileged operation) 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-0362 for the canonical procedure and remediation.

Tools (optional)

• Siri

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 shortcut

Real-world references

Concrete public disclosures that match this vulnerability class:

• Apple: App Intents (Siri / Spotlight / Widgets / Controls / Action Button / Apple Intelligence surfaces)