printing a blob URL is blocked

[msulja]

I don't see any existing posts on this issue so I figured I would post to see if anyone else is experiencing the issue. When previewing a file on Box.com, there is a drop-down menu that has a print option and this allows you to print the document. About a week ago, this would work fine, it would show the Chrome print options dialog. Now what happens is that you can briefly see it flash as if it is trying to open the dialog box but it closes right away. Uninstalling or disabling Adblock Plus makes it start working again. When the first user reported it two days ago (10/2), I thought it was a random issue with their computer (because it worked fine on mine) and just disabled Adblock on the Box website. Then another user reported it yesterday and then when I tested on mine again, it was indeed broken for me. Since this just started happening for a number of users, I 'think' it is related to the latest version of Adblock but I'm not sure how the auto-update of extensions work (last updated Adblock version shows Sept 26 on the store) so it could also be due to a Chrome update which is now causing Adblock to act differently. One thing I noticed is on certain file types (Office documents and PDFs), Box opens a new tab with a 'blob' URL to the file (syntax below) before it launches the Chrome print dialog. If it's a picture (PNG, etc) then it doesn't launch the blob tab and the print dialog works fine. This leads me to believe that if any website (and not just Box) that opened a new tab with a blob URL and attempted to print, Adblock would probably block it as well. I tried testing on Dropbox and OneDrive but they print using a different method instead of a blob URL, not sure what other website this sort of behavior would exist where we could test that.

blob:https://(file URL)

If you have a Box account (or make a free one), you can reproduce it. I am able to reproduce this on Windows 7 and Windows 10 Pro 64-bit in our environment and a quick fix is to whitelist the Box website. However, we push out the Adblock Plus extension to all of our users with group policy and it is not feasible to go to everyones computer to change this. If there was an easy way to whitelist the domain on all the computers with group policy, I would be open to that but after reading a number of posts, it doesn't seem that is possible. It looks like there is an old issue submitted here (https://issues.adblockplus.org/ticket/420) but it doesn't appear to be going anywhere. This functionality was working just fine until a few days ago and I don't think Adblock should be blocking blob prints? Or did I miss something entirely as I looked into this issue?

Environment
Win 7 Pro 64-bit
Chrome 61.0.3163.100 (64-bit)
Adblock Plus 1.13.4

[mapx]

Provide simple steps to reproduce the issue (provide test account, link, explain all the steps to reproduce the issue)

or/and read carefully
forum/viewtopic.php?f=10&t=43791

and post here only the blocked items (and the triggered filters) you see in the panel.

[msulja]

Thank you for providing that link. The blocked blob item was being blocked by the EasyList (|blob:$popup EasyList). I then verified that adding the custom filter "@@blob:https://*.box.com/$popup" works to override the EasyList subscription.

I then made my own subscription filter, uploaded it to our website and then using the group policy details located here (https://issues.adblockplus.org/ticket/3801) I was able to push out these settings to all my users.

All fixed, thank you!