This attack doesn't seem to work in 64.0.3282.119 and later on Windows; the prompt dialog causes the full-screen mode to exit immediately.

In contrast, the spoof seems to work perfectly on Mac.

What is the behavior that you see?

On my Mac, in 65.0.3315.3 I see:
1. The page goes fullscreen
2. The page loads a gmail spoof image
3. The page shows a dialog, kicking it out of fullscreen
4. The page is shown non-fullscreen but with a dialog attached.

On my Mac I cannot repro a failure to exit fullscreen.

Re #2: I'm not kicked out of full-screen by the prompt on Mac. I tried changing chrome://flags#secondary-ui-md but that didn't make a difference.

What Mac OS are you using? I'm on 10.11 and things work.

10.13.2 (17C205) on a 2015 MacBook Pro.

I'm seeing the same behavior as elawrence on a 2012 Macbook Pro with 66.0.3331.0.

avi: I hope you don't mind me assigning this to you so that it has an owner.

What is your OS version?

Same as Eric, High Sierra (10.13.2)

I can also repro, albeit on High Sierra with M63. It's fairly nasty as the escape key doesn't seem to exit fullscreen. 

Sarah, has fullscreen changed in 10.13? Popups kick pages out of fullscreen in 10.11.

Yes, it looks like the fullscreen transition process has changed on 10.13. This broke some stuff recently. I can take over this issue and have a look

That would be awesome. I'll stick around; if there are any issues related to dialogs that you need a hand with, poke me.

Attaching a file to easily go into fullscreen and trigger popups.

Deleted: fullscreenpopuptest.html 933 bytes

fullscreenpopuptest.html 933 bytes View Download

Thanks! I suspect this is an async issue. I was the one who fixed this on 10.12 and earlier, so I have a good idea on where to look.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/a390da5e987c936ca7785d948c635ea67da02552

commit a390da5e987c936ca7785d948c635ea67da02552
Author: spqchan <spqchan@chromium.org>
Date: Thu Feb 08 20:55:42 2018

[Mac] Fix Fullscreen Spoofing Issue on 10.13

On 10.13, -didEnteredFullscreen: is called before the
fullscreen transition actually gets finished. As a result,
AppKit ignores -toggleFullscreen: inside that runloop and will
print "not in a fullscreen state". To fix this issue, call
-toggleFullscreen: asynchronously.

Bug:  806162 
Change-Id: If0d3559c68bfb38ba70da86894f1231f976ee403
Reviewed-on: https://chromium-review.googlesource.com/909080
Reviewed-by: Avi Drissman <avi@chromium.org>
Commit-Queue: Sarah Chan <spqchan@chromium.org>
Cr-Commit-Position: refs/heads/master@{#535506}
[modify] https://crrev.com/a390da5e987c936ca7785d948c635ea67da02552/chrome/browser/ui/cocoa/browser_window_controller.mm
[modify] https://crrev.com/a390da5e987c936ca7785d948c635ea67da02552/chrome/browser/ui/cocoa/browser_window_controller_private.h
[modify] https://crrev.com/a390da5e987c936ca7785d948c635ea67da02552/chrome/browser/ui/cocoa/browser_window_controller_private.mm

spqchan: Uh oh! This issue still open and hasn't been updated in the last 14 days. This is a serious vulnerability, and we want to ensure that there's progress. Could you please leave an update with the current status and any potential blockers?

If you're not the right owner for this issue, could you please remove yourself as soon as possible or help us find the right one?

If the issue is fixed or you can't reproduce it, please close the bug. If you've started working on a fix, please set the status to Started.

Thanks for your time! To disable nags, add the Disable-Nags label.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

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Congrats! the Chrome VRP panel decided to award $1,000 for this report. Cheers!

This bug requires manual review: M66 has already been promoted to the beta branch, so this requires manual review
Please contact the milestone owner if you have questions.
Owners: cmasso@(Android), cmasso@(iOS), josafat@(ChromeOS), abdulsyed@(Desktop)

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot

Since this landed before March 1st, no merge needed for 66. 

This bug has been closed for more than 14 weeks. Removing security view restrictions.

For more details visit https://www.chromium.org/issue-tracking/autotriage - Your friendly Sheriffbot