In what many sources at the company said is a major push, Yahoo is working on a massive plan to overhaul its brand in order to repair a damaged public image and focus consumers on what defines Yahoo.The effort is being spearheaded by newly installed Chief Marketing Officer Elisa Steele, who has hired well-known brand consulting firm Landor Associates, as well as an outside consultant named Penny Baldwin, who was a former top exec at brand and ad giant Young & Rubicam.