It all depends on the meaning of that extension. If Norton Security is configured in Interactive/Semi-auto mode, it will ask you to confirm apps that are allowed to run when computer starts. You should read the notification provided by Norton. It also provides the details regarding its malware status. Based on that info you will accept or deny it from running.
If the extension popped out of nowhere, then I recommend removing it from startup because it could be malware and a computer scan is recommended.