Description

webpack-dev-server users' source code may be stolen when they access a malicious web site with non-Chromium based browser

Summary

Source code may be stolen when you access a malicious web site with non-Chromium based browser.

Details

The Origin header is checked to prevent Cross-site WebSocket hijacking from happening which was reported by CVE-2018-14732. But webpack-dev-server always allows IP address Origin headers. https://github.com/webpack/webpack-dev-server/blob/55220a800ba4e30dbde2d98785ecf4c80b32f711/lib/Server.js#L3113-L3127 This allows websites that are served on IP addresses to connect WebSocket. By using the same method described in the article linked from CVE-2018-14732, the attacker get the source code.

related commit: https://github.com/webpack/webpack-dev-server/commit/72efaab83381a0e1c4914adf401cbd210b7de7eb (note that checkHost function was only used for Host header to prevent DNS rebinding attacks so this change itself is fine.

This vulnerability does not affect Chrome 94+ (and other Chromium based browsers) users due to the non-HTTPS private access blocking feature.

PoC

Download reproduction.zip and extract it

Run npm i

Run npx webpack-dev-server

Open http://{ipaddress}/?target=http://localhost:8080&file=main with a non-Chromium browser (I used Firefox 134.0.1)

Edit src/index.js in the extracted directory

You can see the content of src/index.js

The script in the POC site is:

window.webpackHotUpdate = (...args) => {
    console.log(...args);
    for (i in args[1]) {
        document.body.innerText = args[1][i].toString() + document.body.innerText
	    console.log(args[1][i])
    }
}
...
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Impact

This vulnerability can result in the source code to be stolen for users that uses a predictable port and uses a non-Chromium based browser.

Mitigation

Aliases

References