It has ASCII characters(Which most public plugins don't support)so it is most likely custom, but you can easily find plugins like this. You should search for Custom Scoreboard Plugins.
I know it's not custom, but thanks for the insight. I'll keep looking, if anyone knows, I still haven't found it.
That's Info-Board. You can customize the Rank, Online Players, etc. with variables( look like {<name>} )