(#) `addJavascriptInterface` Called !!! WARNING: `addJavascriptInterface` Called This is a warning. Id : `AddJavascriptInterface` Summary : `addJavascriptInterface` Called Severity : Warning Category : Security Platform : Android Vendor : Android Open Source Project Feedback : https://issuetracker.google.com/issues/new?component=192708 Since : Initial Affects : Kotlin and Java files Editing : This check runs on the fly in the IDE editor See : https://developer.android.com/reference/android/webkit/WebView.html#addJavascriptInterface(java.lang.Object,%20java.lang.String) See : https://support.google.com/faqs/answer/9095419?hl=en See : https://goo.gle/AddJavascriptInterface Implementation : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-checks/src/main/java/com/android/tools/lint/checks/AddJavascriptInterfaceDetector.kt) Tests : [Source Code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/AddJavascriptInterfaceDetectorTest.kt) Copyright Year : 2014 For applications built for API levels below 17, `WebView#addJavascriptInterface` presents a security hazard as JavaScript on the target web page has the ability to use reflection to access the injected object's public fields and thus manipulate the host application in unintended ways. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/test/pkg/AddJavascriptInterfaceTest.java:16:Warning: WebView.addJavascriptInterface should not be called with minSdkVersion < 17 for security reasons: JavaScript can use reflection to manipulate application [AddJavascriptInterface] webView.addJavascriptInterface(object, string); ---------------------- src/test/pkg/AddJavascriptInterfaceTest.java:23:Warning: WebView.addJavascriptInterface should not be called with minSdkVersion < 17 for security reasons: JavaScript can use reflection to manipulate application [AddJavascriptInterface] webView.addJavascriptInterface(object, string); ---------------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `src/test/pkg/AddJavascriptInterfaceTest.java`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~java linenumbers package test.pkg; import android.webkit.WebView; import android.content.Context; @SuppressWarnings({"ClassNameDiffersFromFileName", "MethodMayBeStatic"}) public class AddJavascriptInterfaceTest { private static class WebViewChild extends WebView { WebViewChild(Context context) { super(context); } } private static class CallAddJavascriptInterfaceOnWebView { public void addJavascriptInterfaceToWebView(WebView webView, Object object, String string) { webView.addJavascriptInterface(object, string); } } private static class CallAddJavascriptInterfaceOnWebViewChild { public void addJavascriptInterfaceToWebViewChild( WebViewChild webView, Object object, String string) { webView.addJavascriptInterface(object, string); } } private static class NonWebView { public void addJavascriptInterface(Object object, String string) { } } private static class CallAddJavascriptInterfaceOnNonWebView { public void addJavascriptInterfaceToNonWebView( NonWebView webView, Object object, String string) { webView.addJavascriptInterface(object, string); } } } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://cs.android.com/android-studio/platform/tools/base/+/mirror-goog-studio-main:lint/libs/lint-tests/src/test/java/com/android/tools/lint/checks/AddJavascriptInterfaceDetectorTest.kt) for the unit tests for this check to see additional scenarios. The above example was automatically extracted from the first unit test found for this lint check, `AddJavascriptInterfaceDetector.test`. To report a problem with this extracted sample, visit https://issuetracker.google.com/issues/new?component=192708. (##) Suppressing You can suppress false positives using one of the following mechanisms: * Using a suppression annotation like this on the enclosing element: ```kt // Kotlin @Suppress("AddJavascriptInterface") fun method() { addJavascriptInterface(...) } ``` or ```java // Java @SuppressWarnings("AddJavascriptInterface") void method() { addJavascriptInterface(...); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection AddJavascriptInterface problematicStatement() ``` * Using a special `lint.xml` file in the source tree which turns off the check in that folder and any sub folder. A simple file might look like this: ```xml <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="AddJavascriptInterface" severity="ignore" /> </lint> ``` Instead of `ignore` you can also change the severity here, for example from `error` to `warning`. You can find additional documentation on how to filter issues by path, regular expression and so on [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html). * In Gradle projects, using the DSL syntax to configure lint. For example, you can use something like ```gradle lintOptions { disable 'AddJavascriptInterface' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore AddJavascriptInterface ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).