However, the sources said that the hiring of a writer does not mean that the project has been give a go-ahead at the studio.
Scarlett will reprise her character in "Avengers: Infinity War" and "Avengers 4".
Schaeffer has written the 2014 Blacklist pick "The Shower", a sci-fi action comedy with Anne Hathaway attached to star and produce.
She also wrote "Nasty Women", a remake of "Dirty Rotten Scoundrels", starring set to star Hathaway and Rebel Wilson.
While DC found success with its first female-fronted stand alone movie in "Wonder Woman", Marvel is yet to open its account with Brie Larson-starrer "Captain Marvel".
If 'Black Widow' comes to be a reality, it will be Marvel's second superhero drama, to be led by a woman.
(This story has not been edited by Business Standard staff and is auto-generated from a syndicated feed.)