This is, "Look at You, Hacker"
Killed 50 enemies using only hacked Security.
You must get 50 kills with just hacked cameras, turrets and mini-turrets (thanks to ehcubed for verifying this).Not sure if Medical Stations will work, they can be hacked and can kill enemies, so they should.
I got this in the 3rd area in Rapture (forget the name, but where you meet the crazed Fisherman/Father Whales).
Some tips, when doing a Gather, always get two bots. You can do this by finding a machine to hack and stopping it in the red, quickly shutdown the security and hack the bots. This will give you great protection, they always seem to notice enemies before the player. If possible, stop it in the blue when hacking the bots, this'll make them even stronger.