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Re: [mediacapture-screen-share] Add getCurrentBrowsingContextMedia (#148)

From: Elad Alon via GitHub <sysbot+gh@w3.org>
Date: Fri, 26 Mar 2021 00:09:37 +0000
To: public-webrtc-logs@w3.org
Message-ID: <issue_comment.created-807783336-1616717376-sysbot+gh@w3.org>
> I'd be opposed to standardizing any parameter related to this, because I think it's bad for privacy for the reasons stated.

The attacks we have discussed so far all required a single frame to perform. A malicious application can preload occluded cross-origin iframes and flash them to the screen for the duration of a single frame immediately after the user approves screen-capture. As soon as the user approves, it becomes too late to hide anything from the app. Switching tabs, minimizing windows, etc. - such steps do not offer protection from a malicious app. The decisive moment is when the user accepts.

Currently, Safari offers only the entire screen; Chrome and Edge offer screen/window/tab, with the first option on offer being screen. Most users have a single screen, and it's showing the current tab at the moment capture starts. Any danger that exists with capturing the current tab, also exists when capturing the current screen - and more (e.g. see titles of other tabs).
 
Dialogs offering unconstrained choice to the user, but with focus moved away from current-screen towards current-tab, are more secure than dialogs that push towards sharing the entire screen. Helping browsers move to more secure options creates a more secure Web. In order to be implemented, it helps if work on `getViewportMedia` in Chrome is motivated by a Google product that has immediate need for it. A product that intends to use it, and is therefore interested in funding that work.

If you can help me find a variation that satisfies everyone¹, or that can be an acceptable compromise for everyone, I would be very grateful. This can include any old/new idea, or any temporary compromise. I believe it will also be good for security and privacy on the Web.

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¹ Including one customer for this feature which will only be able to adopt COOP+COEP in the mid-term future, and the new header only in the long-term future. And this customer is the motivation for our investment of headcount in this.

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GitHub Notification of comment by eladalon1983
Please view or discuss this issue at https://github.com/w3c/mediacapture-screen-share/pull/148#issuecomment-807783336 using your GitHub account


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