URI Permission / GRANT_URI_PERMISSIONS Abuse

← Improper Platform Usage

grant_uri_permission_abuse   HARD

Description

A forwarded/redirected Intent carries FLAG_GRANT_READ/WRITE_URI_PERMISSION to a private content:// URI, so a malicious app is transitively granted access to files it should not reach (Pixel CVE-2024-27222 Intent-redirect + grant-URI class).

How it works

The app receives an Intent from an untrusted caller and forwards it onward without stripping the grant flags. The forwarded Intent still carries FLAG_GRANT_READ/WRITE_URI_PERMISSION pointing at a private content:// provider URI the app can read, so the transitive grant reaches the attacker-chosen target, handing a malicious app read/write access to files it should never reach (Pixel CVE-2024-27222 Intent-redirect and grant-URI class). This is an offline, deterministic simulation: the broker returns which package ended up holding the grant. The secure path strips inbound grant flags on redirect and only forwards to a trusted target allowlist.

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 URI Permission / GRANT_URI_PERMISSIONS Abuse (grant_uri_permission_abuse). 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:

• malicious companion app

Real-world references

Concrete public disclosures that match this vulnerability class:

• CVE-2024-27222 (Pixel/Android intent-redirect + grant-URI)