Exported Component -> Arbitrary URL / Activity Launch

← Improper Platform Usage

exported_component_arbitrary_url_activity   MEDIUM

Description

An exported component takes an attacker-supplied URL/activity target and opens it with the app’s identity/privileges (ABEMA CVE-2024-28745 / Samsung Members CVE-2026-20985 & CVE-2025-21079 class).

How it works

An exported component reads attacker-supplied extras naming a URL and/or an activity and opens whatever is named, with this app’s identity and privileges. With no allowlist, another app can point it at an arbitrary URL or, worse, a privileged internal activity (admin, debug, session-export) that should only be reachable in-process (the ABEMA CVE-2024-28745 / Samsung Members CVE-2026-20985 & CVE-2025-21079 class). This is an offline, deterministic simulation: the intent is a map of extras and “opening” returns a descriptor of what would launch. The secure handler allowlists only public activities and first-party https URLs.

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 Exported Component -> Arbitrary URL / Activity Launch (exported_component_arbitrary_url_activity). 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