Telephony / Phone-Account Capability Abuse

← Improper Platform Usage

telephony_capability_abuse   HARD

Description

A loosely-guarded / exported flow lets an untrusted caller drive a telephony capability - place a call, send an SMS, register or manipulate a phone account, redirect/intercept a call - via the Telecom component with no per-invocation permission check, so the app’s real impact is far larger than its visible UI suggests (Android Telecom unauthorized-call permission-bypass CVE-2026-28615 class).

How it works

An exported Telecom-like component drives telephony capabilities (place a call, send an SMS, register a phone account) but performs no per-invocation permission check. An untrusted local app that holds none of the required permissions therefore dials a premium-rate number on the user’s behalf (Android Telecom permission-bypass CVE-2026-28615 class). This is an offline, deterministic simulation, no call is placed. The secure path requires the caller to hold the matching permission plus a per-invocation user confirmation for sensitive actions.

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 Telephony / Phone-Account Capability Abuse (telephony_capability_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-0365 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-2026-28615 (Android Telecom permission bypass -> unauthorized phone call)