Comment by chrisfosterelli
6 years ago
Not sure I follow the CORS angle. The linked stackoverflow question mostly seemed to be someone who was confused about how CORS works, and the issue in the Google Chrome tracker was closed as WontFix because they couldn't reproduce it and said it should work.
I'm nearly positive that CORS from localhost works OK. I set this up all the time for local development. For example, I run a client CRA app on localhost:3000 and an API on localhost:3001. The API sets the CORS headers and the CRA app can make requests to it.
If this is correct then I believe all Zoom needed to do is have their localhost application set CORS headers for their production domain. This would have allowed AJAX communication and only allowed it for Javascript running on their domain. Instead they did this totally hacky method that lets the whole world interact with the localhost server...
Maybe I missed something but if they could have done this the right way and didn't that is much worse IMO...
You're 100% correct, and while someone has pointed out the proper headers that need to be set on the bug report here: https://bugs.chromium.org/p/chromium/issues/detail?id=67743, it's been drowned out by people who don't seem to understand the issue:
http://williambert.online/2013/06/allow-cors-with-localhost-...
CORS is hard, I've struggled on it several times, and I'm not surprised an engineer gave up trying to fix it because of deadlines.
Can confirm, CORS (Origin: ramdomsite.tld to localhost) works just fine in Chrome.
If you have a CORS enable server on localhost you can make requests to it from http://www.test-cors.org
Am I right in thinking that CORS only applies to Javascript-initiated requests? This trick uses an embedded image to make the request.
That's correct, and part of my point. If they used CORS headers correctly it could both be secure and not require a crazy image hack.
The image hack seems like a lot of work to go through to make an app LESS secure.
I'm a bit confused, so CORS doesn't apply when trying to load an image?
If they set CORS to allow interaction from anywhere, why use an image and not load data with js?
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