FC Red Bull Salzburg App 5.1.9-R Improper Authorization

`RCE Security Advisory  
https://www.rcesecurity.com  
  
  
1. ADVISORY INFORMATION  
=======================  
Product: FC Red Bull Salzburg App  
Vendor URL: https://play.google.com/store/apps/details?id=laola.redbull  
Type: Improper Authorization in Handler for Custom URL Scheme [CWE-939]  
Date found: 2023-04-06  
Date published: 2023-06-01  
CVSSv3 Score: 6.1 (CVSS:3.1/AV:N/AC:L/PR:N/UI:R/S:C/C:L/I:L/A:N)  
CVE: CVE-2023-29459  
  
  
2. CREDITS  
==========  
This vulnerability was discovered and researched by Julien Ahrens from  
RCE Security.  
  
  
3. VERSIONS AFFECTED  
====================  
FC Red Bull Salzburg App <= 5.1.9-R  
  
  
4. INTRODUCTION  
===============  
Die FC Red Bull Salzburg-App bietet allen Fans innovative Features, die ein  
modernes Stadionerlebnis ermöglichen.  
  
Mit verschiedenen Livecams, die nur innerhalb der Red Bull Arena abrufbar  
sind und das Spielgeschehen aus unterschiedlichen Perspektiven zeigen, sowie  
auch Sofortwiederholungen aller wichtigen Szenen wird der Besuch in der Red  
Bull Arena auf ein neues Level gehievt.  
  
(from the vendor's homepage)  
  
  
5. VULNERABILITY DETAILS  
========================  
The "FC Red Bull Salzburg App" app for Android exposes an activity called  
"at.redbullsalzburg.android.AppMode.Default.Splash.SplashActivity".  
  
This activity aims to show the contents of a given URL within the app's context.  
However, the app does not properly validate the URL and the intent's data URI,  
which an unauthenticated attacker can abuse to load arbitrary contents into the  
app by either tricking the user into opening a specifically crafted link or using  
a malicious app on the same device.  
  
The specific problem here is the assumed trust between the user having the app  
installed and what the app is actually doing/displaying to the user. So if the  
user sees the app being loaded and automatically redirecting to another page, it  
can be assumed that the user also trusts the loaded page.  
  
  
6. PROOF OF CONCEPT  
===================  
There are two ways to exploit this vulnerability:  
  
1. Via the app's custom URI scheme "fcrbs" followed by any arbitrary URL:  
fcrbs://www.rcesecurity.com  
  
2. Via an explicit intent invocation:  
Intent i = new Intent();  
i.setComponent(new ComponentName("laola.redbull", "at.redbullsalzburg.android.AppMode.Default.Splash.SplashActivity"));  
i.setData(Uri.parse("https://www.rcesecurity.com"));  
startActivity(i);  
  
  
7. SOLUTION  
===========  
None. Uninstall the app.  
  
  
8. REPORT TIMELINE  
==================  
2023-04-06: Discovery of the vulnerability  
2023-04-06: RCE Security sends initial notification to vendor via [email protected] and to [email protected]  
2023-04-06: RCE Security asks Intigriti.com for a security contact because of a disagreement with Intigriti's disclosure terms  
2023-04-06: Intigriti states that they don't hand out contact email addresses of customers  
2023-04-06: MITRE assigns CVE-2023-29459  
2023-04-07: Vendor responds stating to submit everything via Intigriti  
2023-04-07: RCE Security asks for another way to report due to the unacceptable T&Cs of Intigriti  
2023-04-11: Vendor responds stating that a report to [email protected] is sufficient  
2023-04-11: RCE Security provides a preliminary version of this advisory  
2023-04-19: Vendor acknowledges the vulnerability  
2023-04-19: RCE Security extends disclsoure date to its maxiumum of 45 days  
2023-05-07: No Response from vendor  
2023-05-07: RCE Security asks vendor for an update since disclosure date is coming  
2023-05-11: No Response from vendor  
2023-05-11: RCE Security asks vendor for an update  
2023-05-12: Vendor response stating that more time is needed to fix the bug since the developers are not within the organization  
2023-05-15: RCE Security reminds the vendor of the disclosure policy and date  
2023-05-27: No response from vendor  
2023-05-27: RCE Security sends one last notification and adjusted the disclosure date to 01st June 2023  
2023-06-01: No response from vendor  
2023-06-01: Public Disclosure  
  
  
9. REFERENCES  
=============  
https://github.com/MrTuxracer/advisories  
https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2023-29459  
`