In its race to rival Amazon and become the next great “everything store,” Walmart leveraged its brick and mortar empire to grow into a major player online. And it didn’t take long for the world’s biggest retailer to build a massive digital marketplace with hundreds of millions of products and thousands of third-party sellers. But Walmart’s digital boom has a little known and much darker underside – where some sellers steal the identities of legitimate businesses so they can peddle counterfeit and sometimes dangerous products to unsuspecting customers. After CNBC shared its reporting with Walmart, the company began tightening its vetting process for both products and sellers and says it has a “zero-tolerance policy for prohibited or noncompliant products.”