Authorization Based on Mutable Resource State

← Improper Platform Usage

authorization_by_mutable_resource_state   HARD

Description

A security/authorization decision is made on mutable resource existence or state (e.g. doesFileExist() -> grant access -> the file is then created/changed), so an app gains read/write to a resource - including files that do not yet exist - by racing or manipulating that state after the check (Android MediaProvider createRequest file-existence LPE CVE-2026-0035 class).

How it works

A security decision is made on the mutable existence of a resource: “if the file does not exist yet, grant the caller ownership and create it,” decoupling the authorization check from the resource binding. An attacker wins read/write access to a path a victim has legitimately reserved but not yet written (a TOCTOU or logic flaw, the Android MediaProvider CVE-2026-0035 class). This is an offline, deterministic simulation with an in-memory filesystem. The secure path binds authorization to a stable owner identity captured atomically, never to mutable existence.

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 Authorization Based on Mutable Resource State (authorization_by_mutable_resource_state). 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.

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-2026-0035 (Android MediaProvider read/write to non-existing files -> LPE)