The mission starts if you visit the C-Sec Office in the Citadel Embassies.
Talk to Jondum Bau located near Baileys office to add the Hanar Diplomat Citadel mission to your journal.
When to start
“Salarian Spectre Jondum Bau suspects that a member of the Hanar diplomatic staff is indoctrinated.
Find evidence on the Hanar in the Presidium Embassies.”
Credits, Experience, Hanar and Drell War Asset (if Paragon), Spectre Unit War Asset (if Renegade)
To complete the Hanar Diplomat go to Citadel Embassies, and assuming that you have followed our Mass Effect 3 walkthrough up to this point, visit the Spectre Office (point 3).
Access the Terminal and select Hanar Embassy Tracking.
Now, return to the elevator and check the waiting room, to the left.
Bypass the terminal on the wall, then go to the Docks: Holding Area and repeat the step on the terminal near the elevator, and on the one located on the other side of the area.
Now, return to the second terminal, and access it, then go to Jondam Bau in the Embassies area.
Talk to Jondam Bau and the Hanard Diplomat. During the final cutscene you have two options:
-You can stop the virus (Paragon Decision), but Jondam Bau dies.
-You can save Jondam Bau (Renegade)
NOTE: Many players reported that the Hanar Diplomat mission is bugged, and the terminals can’t be accessed. A good idea is to save the game before starting this quest, and if the terminals become inaccessible, you should retrace the quest by loading the last save.