Element hiding unapplied when anonymous iFrame content added via document.write

[greiner]

Environment

Chrome 45
Adblock Plus 1.9.3

How to reproduce

1. Add ##.hide filter to Adblock Plus.
2. Clone ​gist.
3. Set up local static server for the file and navigate to it in the browser.

Observed behavior

"This text should be hidden" shows up next to "Subframe (document.write)".

Expected behavior

"This text should be hidden" doesn't show up anywhere on the page.

[sebastian]

Reproduced and identief as regression caused by ​a400e15525fc.

[sebastian]

I'm afraid I wouldn't be able to look any deeper into this issue anytime soon. @greiner: Would you mind?

[sebastian]

Please create a separate issue for Maxthon. There effected code here isn't shared between Chrome and Maxthon.

[sebastian]

I figured out that content scripts don't run again after document.write() has been called, replacing the DOM and therefore also removing our stylesheet. I'm not even sure if this is a bug, as it's not really a new document but merely replacing it's entire content, which could be achieved as well with the DOM API.

However, stylesheets injected with chrome.tabs.insertCSS persist. Also, due to other issues we had and still have with injecting a stylesheet into the DOM using a content script (with and without Shadow DOM), I'm in the favor to use chrome.tabs.insertCSS as soon as ​frame IDs are supported.

But with our current approach, there seems to be no great workarounds. The nodes that are removed/overridden by document.write() aren't reported by a MutationObserver. Theoretically, we could still poll (once a second or so) whether our stylesheet is still in there. But that would obviously impair performance, and the content to be blocked would still show up for a notable amount of time.

I'm making this issue confidential as it provides a way to circumvent Adblock Plus.

[scheer]

New issue created for Maxthon and also marked as confidential. https://issues.adblockplus.org/ticket/3526#comment:1

[mjethani]

This is no longer an issue with user style sheets.

[sebastian]

Well, there are element hiding emulation filters (and potentially other anti-circumvention measures implemented in content scripts in the future) that would still be effected.

[mjethani]

This seems to have got fixed once we moved to user style sheets on ​Firefox (#5090) and ​Chrome (#242).

For element hiding emulation, we only use style="display: none !important" now (#6504). If we ever go back to using style sheets, it will be user style sheets. I think we can close this now.

[mjethani]

Also let's remove the confidential flag.

[sebastian]

Closing this issue as per comment:12. If still relevant, please file a new issue on ​GitLab.