To get defender and attacker progress all you have to do is destroy kill streaks while attacking or defending an objective. This can be done in HQ, HP, Dom, ground war, etc. I recommend ground war because there are a lot of streaks plus you will get your ground streak progress as well. Just make sure you are standing on a point you are defending or attacking.
Even if this is unintentional I like it as it allows the player to get the challenge done while helping the team. I'll try to make sure this stays as a valid strategy for these unlocks.