Confused-Deputy Intent Validation Bypass

← Improper Platform Usage

confused_deputy_intent_validation   HARD

Description

A privileged component performs an action on behalf of a caller after only a superficial Intent check, letting a local app abuse the app’s privileges (Android Settings CVE-2025-32326 / CVE-2025-32321 confused-deputy class).

How it works

A privileged, exported component performs a protected action (for example writing a secure setting) on behalf of a caller after only a superficial check: it validates the requested action string but never verifies the caller’s identity or permission. A local, unprivileged app crafts the Intent and the deputy carries out the privileged operation for it (Android Settings CVE-2025-32326 / CVE-2025-32321 confused-deputy class). This is an offline, deterministic simulation: the deputy returns whether it performed the action and for whom. The secure path verifies the caller actually holds the required permission before acting.

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 Confused-Deputy Intent Validation Bypass (confused_deputy_intent_validation). 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-0364 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-2025-32326 (Android Settings)
• CVE-2025-32321 (Android Settings)