ClipData URI-Grant Leakage

← Improper Platform Usage

clipdata_uri_grant_leakage   MEDIUM

Description

The app attaches a private content:// URI to an Intent’s ClipData (or copies it) together with FLAG_GRANT_READ_URI_PERMISSION and fires it to an implicit / untrusted target, unintentionally FORWARDING a read capability for its own provider data to another app. The grant rides silently on the ClipData rather than the data URI. Distinct from clipboard text theft: this leaks a capability, not a value. The secure path sends explicit intents to a pinned package and never grants on ClipData bound for untrusted resolvers (Android ClipData-grant class).

How it works

The app attaches a private content:// URI (backed by its own provider) to an Intent’s ClipData together with FLAG_GRANT_READ_URI_PERMISSION and fires it to an implicit or untrusted target. Android propagates the read grant to every URI in the ClipData, not just the visible data URI, so whichever app catches the intent silently inherits read access to the private provider. The grant rides on the ClipData, which makes it easy to miss, and it leaks a capability, not just a copied value. This is an offline, deterministic simulation. The secure path sends an explicit intent to a pinned package and never grants on ClipData bound for an untrusted resolver.

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 ClipData URI-Grant Leakage (clipdata_uri_grant_leakage). 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-0357 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 intent with ClipData content:// URI

Real-world references

Concrete public disclosures that match this vulnerability class:

• Android: ClipData URI grants and FLAG_GRANT_READ_URI_PERMISSION