Go to Citadel and as soon as you come out of the C-sec, head left into the room right before the stairs leading to level 26. There should be two Asaries sitting on a sofa. To start a conversation with them, stand in the center of the room, you will overhear a conversation and your journal will be up-dated. Then you can go to them and give them the forged ID.
If you cant find them, try again later or completing Thane's side quest first to increase the chance to encounter the Asaries because it appears to be random.