There IS a security check when connecting INT/ INT at OSL, but as relatively few passengers connect INT/ INT at OSL waiting time is usually very short. Be aware that the INT/ INT security isn't open at all times, so you might at times have to go through customs and use the main departure security checkpoint (same procedure as passengers connecting INT/DOM). It should be open at that time of day, but if you are on a through ticket, or your incoming flight is on time, you should have sufficient time even if you have to go through main security, as this is the usual connecting time INT/DOM when you have to wait for your luggage and recheck it before going tthrough security