CoStar Group Inc., a major provider of real estate information and analytics, has escalated its legal battle against Zillow Group Inc., alleging ongoing mass copyright infringement. In a lawsuit first filed in July, CoStar accuses Zillow of continuing to display and distribute tens of thousands of CoStar-owned real estate photographs, many of which are clearly marked with CoStar's distinctive watermark. Despite the lawsuit, Zillow is reportedly displaying thousands of additional infringing images and has not removed many of those previously identified. CoStar claims the images are also being shared with Zillow's partners, including Redfin and Realtor.com, as well as affiliate websites. The company is seeking permanent injunctive relief and substantial damages as it pursues the case.