Hello,

Today I noticed that every five minutes or so an application will self-execute on this chromebook. It has no name, and if it is in the task manager, I can't find it via name, as it has none (image: note the small box above the icon where the name should be), nor via its icon.
https://imgur.com/qJYi9HC

Also, when this machine first boots, prior to running anything myself, it displays the text "Modded by symos // Mobilism.org" (image). Furthermore, it would appear this app is also serving ads straight to the desktop, as that happened today for the first time as well. Turning off WiFi seems to prevent the app from running.
https://imgur.com/8UhZdhK

Any idea what's causing this?

Download an adware malware cleaner. Tell it to start on next reboot and reboot the thing. Should give a starting point