Framer Preview 12 Content Injection Vulnerability

1. ADVISORY INFORMATION
=======================
Product:        Framer Preview
Vendor URL:     https://play.google.com/store/apps/details?id=com.framerjs.android
Type:           Improper Export of Android Application Components [CWE-926]
Date found:     2020-09-06
Date published: 2020-09-22
CVSSv3 Score:   5.5 (CVSS:3.1/AV:L/AC:L/PR:N/UI:R/S:U/C:N/I:H/A:N)
CVE:            CVE-2020-25203


2. CREDITS
==========
This vulnerability was discovered and researched by Julien Ahrens from
RCE Security.


3. VERSIONS AFFECTED
====================
Framer Preview 12


4. INTRODUCTION
===============
Framer Preview is the best way to view and interact with your Framer X and Framer 
Classic projects on Android phones and tablets.

(from the vendor's homepage)


5. VULNERABILITY DETAILS
========================
The "Framer Preview" app for Android exposes an activity to other apps called
"com.framer.viewer.FramerViewActivity". The purpose of this activity is to show
contents of a given URL via an fullscreen overlay to the app user.

However, the app does neither enforce any authorization schema on the activity
nor does it validate the given URL. 

This can be abused by an attacker (malicious app) to load any website/web content 
into the fullscreen overlay. An exemplary exploit could look like the following:

Intent i = new Intent();
i.setComponent(new ComponentName("com.framerjs.android", "com.framer.viewer.FramerViewActivity"));
i.setAction("android.intent.action.VIEW");
i.setData(Uri.parse("https://www.rcesecurity.com"));
startActivity(i);


6. RISK
=======
A malicious app on the same device is able to exploit this vulnerability to lead
the user to any webpage/content. The specific problem here is the assumed trust
boundary between the user having the Framer Preview app installed and what the app
is actually doing/displaying to the user. So if the user sees the app being
loaded and automatically loading another page, it can be assumed that the loaded 
page is also trusted by the user.