CoStar Realty has filed a copyright infringement lawsuit against real estate listings platform RealMassive. The subsidiary of CoStar Group claims RealMassive is illegally using its photos in promotional materials. The lawsuit was filed in federal court in Texas. CoStar CEO Andrew Florance (whom we snapped last year at a Bisnow event) also says RealMassive is not a sharing platform as it claims. "Despite its rhetoric, the company is not a sharing platform," he said in the suit, The Real Deal reports. "Rather, it is a subscription service that appears to be powered by content that is stolen from those who created it through hard work and investment.” CoStar recently acquired ApartmentFinder.com to pair with its Apartments.com property, while RealMassive just announced an $8M funding round with a valuation at $20M. [TRD]