App Intent / Siri Parameter -> Privileged Action (No Authz)

← Improper Platform Usage

app_intent_parameter_authorization   HARD

Description

An App Intent / Siri / Shortcuts / Spotlight entry point maps an untrusted, system-supplied parameter straight to a privileged app action (transfer, delete, export) with no per-invocation authorization or ownership check, so a crafted shortcut invokes the action on the user’s behalf (Apple App Intents capability-confusion class).

How it works

An App Intent, Siri, Shortcuts, or Spotlight entry point maps an untrusted, system-supplied parameter straight to a privileged app action (transfer, delete, export) with no per-invocation authorization and no ownership check. A crafted shortcut here names another user’s account id and the app exports it directly from the parameter, capability confusion where the intent’s privilege is applied to an entity the invoker does not own (the Apple App Intents class). This is an offline, deterministic simulation over a tiny in-memory bank. The secure path requires the invocation to carry a verified user-authorization token and checks the current user owns the target entity, refusing the unauthorized or other-user parameter.

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 App Intent / Siri Parameter -> Privileged Action (No Authz) (app_intent_parameter_authorization). 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.

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:

• Discover new capabilities in the App Intents framework (WWDC26)
• CVE-2026-43704 (iOS Web Extension privileged-capability class)