The dark world of cybercrime has evolved from one of rogue individuals to a functioning market-based economy with its ups and downs, code of conduct and “innovation.” A study by Rand Corp. and commissioned by the security firm Juniper Networks found a well-organized, multibillion-dollar underground economy that has become “a playground of financially driven, highly organized and sophisticated groups.” The evolution of cybercrime creates new challenges for security professionals trying to protect computer networks, says Nawaf Bitar, Juniper’s general manager for security. Juniper’s security vice president Michael Callahan said this cyber underground has all the characteristics of an economy, including its own currencies — chiefly cryptographic payment forms such as Bitcoin.