Can a Windows Acrobat Reader DC plugin communicate with a service via a socket when "Run in AppContainer" is checked?

Report · May 27, 2019

I recently discovered an issue with a plugin that my company created for use with Adobe Acrobat Reader DC on Windows. Specifically, the plugin uses a socket to communicate with a custom service running on the local machine (it just connects to localhost using a port number around 50000). After installing 19.010.20091 (from Feb. 12/19), the plugin was able to connect to the service correctly & could send/receive messages as required. With 19.010.20099 (from Apr. 9/19) & newer, however, the plugin fails to make the connection.

After some investigation, I discovered that the difference is the "Run in AppContainer" checkbox. This defaults to off in the older version, but on in the newer versions. If I manually turn it on in the older version, I see the same problem; turning it off in the newer version allows the plugin to work.

I read Sandbox Protections — Acrobat Application Security Guide & tried to see if I could set something in ProtectedModeWhitelistConfig.txt to enable this, but to no avail. I also briefly read about cross-domain configurations (it kept coming up in my searches for "Acrobat" and "sockets"), but it doesn't seem relevant. I also went through Protected Mode to see if there was anything applicable, but I didn't come across anything.

I realize that I can simply uncheck the box (and we could configure our product's installer to edit the Registry appropriately), but I was wondering if there was an alternate way to do this without disabling this security feature.

I should also mention that we do already have a broker process to handle some other function calls (like a custom capture call that can launch one of our apps if needed), so I could explore moving some of this connection logic in there. I just thought I'd check if this had the potential to resolve this.

I'm quite new to our Adobe plugin code & Broker code, so I would appreciate any help. Also, I might not be able to provide specific code snippets, but if there's something that would be beneficial let me know & I'll see what I can do.

Thanks in advance.