Cordova Android versions up to 3.5.0 would launch any and all external applications by URL. Any URL not explicitly whitelisted was sent to the Android intent system for handling. This was the cause of the security vulnerabilities reported by IBM and disclosed in CVE-2014-3502.
Cordova Android 3.5.1 was released to fix this, which it did by disabling explicit intents, and explaining how to use a plugin to block other URL schemes if desired.
We want to have a better official solution than this, so that developers can easily configure which applications (sms, email, maps, etc) should be launchable from their Cordova app.
The proposed solution is to maintain a second whitelist within the app, for URL patterns which may be used to launch external applications. Then, on URL loading, these tests will occur (in order):
- URLs which are whitelisted internally (existing list) will cause internal navigation
- URLs which are whitelisted externally (new list) will attempt to launch an intent to handle it
- URLs which are not whitelisted at all (in neither list) will be blocked.
URLs can be added to the new (external) whitelist through an extension to the config.xml whitelist syntax:
(Any non-empty value for the launch-external attribute will be considered "true" when parsing the config.xml file)
Open questions (one about forward-thinking security, the other about backwards-compatibility):
- What should the default external whitelist be in the application template that we ship? This will be the case for new apps build with 3.6.0.
- What should the default external whitelist be when there are no <access launch-external="yes"> tags in config.xml? This will be the case for apps which are upgrading to 3.6.0.