Where did Helmut Zemo get all his HYDRA knowledge?

Question

Helmut Zemo, the main antagonist of Captain America 3: Civil War, shows a rather odd level of knowledge about HYDRA operations throughout the movie.

For example, he seems to know a lot about the Winter Soldier program and UN security protocols, including:

That there's a code book to control Bucky, who has it, that Barnes did "something bad" in 1991, and how to impersonate the UN shrink.

He intends is to use this knowledge against the Avengers, and he clearly has enough information to formulate a complex and involved plan.

However, he also seems to be missing a lot of details, including the key facts of:

where the Winter Soldier base is, and what Barnes actually did on that day.

Is there any explanation how Zemo, who otherwise shows no indication of being anyone special or unusual, came into all of this knowledge.

Answer 1

Zemo states that he got it from the S.H.I.E.L.D. and Hydra info that Black Widow released online in Captain America: The Winter Soldier.

Councilman Rockwell: [to Natasha who is on the computer] What are you doing?

Alexander Pierce: She's disabling security protocols and dumping all the secrets onto the Internet.

Natasha Romanoff: Including HYDRA's.

...

Natasha Romanoff: Done. [she looks at her mobile device] And it's trending.

He was able to decrypt some of it and find the location of Vasily Karpov, the Winter Soldier's old handler, who had a book with information on the Winter Soldier project in it, including the trigger words.

Zemo: When S.H.I.E.L.D. fell, Black Widow released Hydra files to the public. Millions of pages. Much of it encrypted, not easy to decipher, but... I have experience... and patience. A man can do anything if he has those.

Falcon and the Winter Soldier also reveals that he his family has a history with Hydra, giving him additional resources.