By their standards the janitors who work at the CIA are also undercover agents.
Technically being employed at CIA is classified and employees have some form of "cover" job at some other federal agency or a cooperative business.
My wife's late uncle was a senior cryptography tech for CIA, often being the cryppie at our embassies, including a stint working out of the Beirut embassy. He got outed by Philip Agee in his 1975 book and could no longer work overseas, but he still kept his cover job.
What was that cover job? Instead of being listed as a cryppie for the CIA his "official" job was as a cryppie in the Pentagon. Brilliant. Of course no foreign spies would be interested in compromising a DOD cryppie, only CIA ones. He actually had an "office" at the Pentagon, which he visited once. It was a broom closet.
I'll bet the cleaning crew at CIA has similar cover jobs, probably as a White House cleaning crew.
Your tax dollars at work.