There are two locations were you can extract, this being behind the warehouse that has a sniper scav that spawns on top between ZB-1011 and old gas. The other is the smugglers boat close to the bridge on on the other side of the map. The "Voron" code is needed to use the extract which can be found in containers(filing cabinets, duffelbags. etc) and on scavs and bosses on the map.