WebViews can be used to display web content as part of a mobile application. A browser engine is used to render and display the content. Like a web
application, a mobile application that uses WebViews can be vulnerable to Cross-Site Scripting if untrusted code is rendered. In the context of a
WebView, JavaScript code can exfiltrate local files that might be sensitive or even worse, access exposed functions of the application that can result
in more severe vulnerabilities such as code injection. Thus JavaScript support should not be enabled for WebViews unless it is absolutely necessary
and the authenticity of the web resources can be guaranteed.
Ask Yourself Whether
- The WebWiew only renders static web content that does not require JavaScript code to be executed.
- The WebView contains untrusted data that could cause harm when rendered.
There is a risk if you answered yes to any of those questions.
Recommended Secure Coding Practices
It is recommended to disable JavaScript support for WebViews unless it is necessary to execute JavaScript code. Only trusted pages should be
rendered.
Sensitive Code Example
import android.webkit.WebView;
WebView webView = (WebView) findViewById(R.id.webview);
webView.getSettings().setJavaScriptEnabled(true); // Sensitive
Compliant Solution
import android.webkit.WebView;
WebView webView = (WebView) findViewById(R.id.webview);
webView.getSettings().setJavaScriptEnabled(false);
See
