Imperial Security Bureau
The Imperial Security Bureau, abbreviated ISB, is an existing organization from Legends.[1]
Palpatine deliberately created three separate Intelligence services (the ISB, Imperial Intelligence and the Ubiqtorate) whose agendas overlapped, to make sure they would clash violently the moment he was gone and could no longer adjudicate their inevitable disputes.[2]
The Imperial Security Bureau was notorious for embedding informers on every major warship or installation, who were equipped with override codes and secret communication channels. Anyone coming into conflict with them could expect demotion or a death sentence, carried out immediately and without recourse. Similarly, the Ubiqtorate had agents within the ISB itself.[2]
After the Battle of Endor, the ISB fought and ultimately lost a fierce battle for dominance with Imperial Intelligence.[2]