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@ -1,15 +1,15 @@
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Using Javascript interfaces in WebViews is unsafe as it allows JavaScript to invoke Java methods,
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potentially giving attackers access to data or sensitive app functionality. WebViews might include
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untrusted sources such as third-party iframes, making this functionality particularly risky. As
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Javascript interfaces are passed to every frame in the WebView, those iframes are also able to
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access the exposed Java methods.
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Using JavaScript interfaces in WebViews to expose Java objects is unsafe. Doing so allows JavaScript
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to invoke Java methods, potentially giving attackers access to data or sensitive app functionality.
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WebViews might include untrusted sources such as third-party iframes, making this functionality
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particularly risky. As JavaScript interfaces are passed to every frame in the WebView, those iframes
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are also able to access the exposed Java object.
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== Ask Yourself Whether
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* The content in the WebView is fully trusted and secure.
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* Potentially untrusted iframes could be loaded in the WebView.
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* The Javascript interface has to be exposed for the entire lifecycle of the WebView.
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* The exposed Java methods will accept input from potentially untrusted sources.
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* The JavaScript interface has to be exposed for the entire lifecycle of the WebView.
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* The exposed Java object might be called by untrusted sources.
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There is a risk if you answered yes to any of these questions.
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@ -18,9 +18,9 @@ There is a risk if you answered yes to any of these questions.
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=== Disable JavaScript
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If it is possible to disable JavaScript in the WebView, this is the most secure option. By default,
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JavaScript is disabled in a WebView, so you do not need to explicitly call
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``webSettings.setJavaScriptEnabled(true)`` in your ``WebSettings`` configuration. Of course, sometimes
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it is necessary to enable JavaScript, in which case the following recommendations should be considered.
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JavaScript is disabled in a WebView, so ``webSettings.setJavaScriptEnabled(false)`` does not need to
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be explicitly called. Of course, sometimes it is necessary to enable JavaScript, in which case the
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following recommendations should be considered.
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=== Remove JavaScript interface when loading untrusted content
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@ -63,7 +63,8 @@ class ExampleActivity : AppCompatActivity() {
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== Compliant Solution
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The most secure option is to disable JavaScript entirely.
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The most secure option is to disable JavaScript entirely. S6362 further explains why it should not be enabled
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unless absolutely necessary.
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[source,kotlin]
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----
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@ -96,7 +97,8 @@ class ExampleActivity : AppCompatActivity() {
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}
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----
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If a JavaScript bridge must be used, consider using ``WebViewCompat.addWebMessageListener`` instead. This allows you to restrict the origins that can send messages to the JavaScript bridge.
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If a JavaScript bridge must be used, consider using ``WebViewCompat.addWebMessageListener`` instead. This allows you to restrict
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the origins that can send messages to the JavaScript bridge.
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[source,kotlin]
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----
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@ -135,3 +137,6 @@ class ExampleActivity : AppCompatActivity() {
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* OWASP - https://owasp.org/www-project-mobile-top-10/2023-risks/m4-insufficient-input-output-validation.html[Mobile Top 10 2024 Category M4 - Insufficient Input/Output Validation]
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* OWASP - https://owasp.org/www-project-mobile-top-10/2023-risks/m8-security-misconfiguration.html[Mobile Top 10 2024 Category M8 - Security Misconfiguration]
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* CWE - https://cwe.mitre.org/data/definitions/79[CWE-79 - Improper Neutralization of Input During Web Page Generation]
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=== Related rules
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* S6362 - Enabling JavaScript support for WebViews is security-sensitive
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