This achievement is for finding and hacking all 26 security cameras around the city.
3 of them are part of missions
16 of them are part of the Drug Bust missions that appear on your map
7 of them are unmarked
If you date Not Ping later in the game it will unlock all the locations on your map but they are available earlier than that. I will post my video guide below that covers the 7 unmarked locations if you wish to get them before dating Not Ping.