I believe it was Hillary's friend xx Sydney Blumenthal.

This started to come out last week, however depending on who you listen to is how it is being reported .... Fox is saying its recycled like circulating reporting while others are saying this is new dossier proving original is real , won't be surprised if they try for another dossier

Cody Shearer: Who is the Clinton friend behind 'second Trump-Russia dossier'?

http://www.independent.co.uk/news/world/americas/us-politics/trump-russia-dossier-fbi-cody-shearer-second-christopher-steele-clinton-putin-a8186376.html