It has no path, no additional details, no explanation to why it's being blocked.
I can't add an exception, see it in the rules or anything. What is this and why is it doing this?
First, take screenshot(s) of the issue and create a log file on your Windows device using Bitdefender Support Tool, by following these steps:
Next, contact Bitdefender Consumer Support by e-mail here (scroll down to the bottom of the page):
with short description of the issue.
After that, you will get an automated reply by the Bitdefender Customer Care Team, with your ticket number.
Now, in reply to that automated reply, you can send the screenshot(s) you already took and the log file you already created in the first step.
Since you are all done, just wait for the support engineers to investigate your issue and find a solution to fix the issue.
Remember that the screenshot(s) and the log file will help a lot to the support engineers for better and faster investigation on your issue and finding a solution.
It appears to be the same as this ticket.
"System has been blocked" firewall. How to override "System" to allow? — The Bitdefender Expert Community
I have encountered this today when dealing with OpenVPN Connect.
Looking at the running processes on the system I'd guess it's the one shown below
Opening the properties of said process via the right click menu seems to point at ntoskrnl.exe. Windows NT OS Kernel at a guess.