NODE_INTEGRATION_ATTACH_EVENT_JS_CHECK

Luca Carettoni edited this page Jan 17, 2019 · 2 revisions

NODE_INTEGRATION_ATTACH_EVENT_JS_CHECK - Disable nodeIntegration for untrusted origins

By default, Electron renderers can use Node.js primitives. For instance, a remote untrusted domain rendered in a browser window could invoke Node.js APIs to execute native code on the user’s machine. Similarly, a Cross-Site Scripting (XSS) vulnerability on a website can lead to remote code execution. To display remote content, nodeIntegration should be disabled in the webPreferences of BrowserWindow and webview tag.


Risk

If enabled, nodeIntegration allows JavaScript to leverage Node.js primitives and modules. This could lead to full remote system compromise if you are rendering untrusted content.

Auditing

It is possible to use the will-attach-webview event to verify (and potentially change) any attribute of webPreferences. This event is emitted when a webview is being attached to the web content.

Since this mechanism can be used to change the webPreferences configuration, carefully review the implementation of the callback. At the same time, this is a powerful mechanism to validate all settings and ensure a secure instance of webview, as demonstrated by this implementation:

app.on('web-contents-created', (event, contents) => {
    contents.on('will-attach-webview', (event, webPreferences, params) => {
        // Strip away preload scripts if unused
        // Alternatively, verify their location if legitimate
        delete webPreferences.preload
        delete webPreferences.preloadURL
        // Disable node integration
        webPreferences.nodeIntegration = false
        // Verify URL being loaded
        if (!params.src.startsWith('https://doyensec.com/')) {
            event.preventDefault()
        }
    })
})

References

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