Play on the Security Tower map in Freeplay Mode, with 1-on-1 settings (Team Size should be set to 1, as should Max Team Size). Start as a Resistance Soldier class. Blow the door to access the next objective, then change to the Operative class. Head toward the safe you are supposed to hack, and make sure not to be killed. When that AI tries to remove your hack box, position yourself on the opposite side of the glass. If you are positioned properly, your enemy will spray the safe ineffectively and you will gain XP, due to the "hacking" and "guarding" you are doing. As long as you aren't positioned too close to the safe, you'll be stuck in a stalemate with your enemy and will earn XP the entire time. Then when you're ready, move closer to the safe to complete the mission and receive your points.