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Vulnerability in the Mac Zoom client allows malicious websites to enable camera

medium.com

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Re: Vulnerability in the Mac Zoom client allows malicious websites to enable camera

#231
Another small thing (big for me) Zoom does is register their app as the handler for `tel:` links every time you launch it, with seemingly no way to disable that. Companies that make themselves the default for something on your machine by force are not to be trusted.

I’m not surprised they start a web server from under their users, and that their response to the vulnerability was lacklustre.

Re: Vulnerability in the Mac Zoom client allows malicious websites to enable camera

#232

From the article: "To shut down the web server, run lsof -i :19421 to get the PID of the process, then do kill -9 [process number]. Then you can delete the ~/.zoomus directory to remove the web server application files."

Does osx not have the fuser command? It lets you find and kill a process by its tcp port (also file handles) in one command. On Linux I use something like 'fuser -k 19421/tcp' to kill server processes all the time. It is super useful when working with local dev servers etc!

It does, but unfortunately without the -k flag.

Re: Vulnerability in the Mac Zoom client allows malicious websites to enable camera

#233
post #2

“On Mac, if you have ever installed Zoom, there is a web server on your local machine running on port 19421.” ... “All a website would need to do is embed the above in their website and any Zoom user will be instantly connected with their video running. This is still true today!”

Does anyone know how this web server starts itself after restarting your machine? As far as I know, a `~/.zoomus` directory can't restart a web server after your machine restarts.

I think it's because it runs on a port higher than 1024, so it doesn't need root privileges to start a web server on that port.

Re: Vulnerability in the Mac Zoom client allows malicious websites to enable camera

#236
post #217

Earlier quoted context omitted.

If Universal Links was supported on macOS we could get the best of both worlds. The web server basically presents meta-data in a JSON-file (in the .well-known directory) which Safari/iOS uses to launch the app if it is installed, and otherwise just renders the webpage [0]. The app contains information about which domains it allows itself to be opened from which would fix this issue. [0]: https://developer.apple.com/l…

Universal Links are better than their localhost webserver insanity, but don't really solve this. A malicious website can still redirect you to a zoom.us URL that will instantly join the meeting without confirmation. The underlying problem is that they want a URL to join a conference call hosted by any random user and share your audio/video without confirmation. And it's simply not safe to trigger that kind of action…

Yes, I agree that's the underlying problem. Regardless of how the URL is opened it shouldn't behave that way.

However, I do think that Universal Links doesn't work with redirects, consider: https://bit.ly/30oxOdO vs https://twitter.com/ycombinator (tap using Safari on iOS with Twitter installed).

EDIT: Turns out I was misinformed...

Re: Vulnerability in the Mac Zoom client allows malicious websites to enable camera

#237

Click on the app icon, hold, move to Trash.

Which isn't actually enough, since the surreptitiously installed server will happily go and reinstall the Zoom client for you whenever you load a zoom link, or a malicious link. You have to kill the server, and remove the ~/.zoomus directory as well. This is all pretty damning to be honest.

Re: Vulnerability in the Mac Zoom client allows malicious websites to enable camera

#239

Click on the app icon, hold, move to Trash.

Just to be sure, I don't think that's enough. You might want to kill the running process and remove the binary (as described under "Quick Fix" section in the blog post)

Re: Vulnerability in the Mac Zoom client allows malicious websites to enable camera

#240

HIPAA provides an effective strategy for holding Zoom’s feet to the fire in cases like this. Since the company markets compliant video conferencing for healthcare professionals, they are classified as a Business Associate. It is quite likely that a well-written complaint on the HHS Office of Civil Rights site would result in further investigation and regulatory action.

software companies tend to be safe from this kind of thing (less everyday though). but they could lose their users
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