Abstract—Cybercrime activities are supported by infrastructures and services originating from an underground economy. The current understanding of this phenomenon is that the cybercrime economy ought to be fraught with information asymmetry and adverse selection problems. They should make the effects that we observe every day impossible to sustain. In this paper we show that the market structure and design used by cyber criminals have evolved towards a market design that is similar to legitimate, thriving, on-line forum markets such as eBay. We illustrate this evolution by comparing the ‘market regulatory mechanisms’ of two underground forum markets: a failed market for credit cards and other illegal goods and another, extremely active marketplace for vulnerabilities, exploits, and cyber attacks in general. The comparison shows that cybercrime markets evolved from unruly, ‘scam for scammers’ market mechanisms to mature, regulated mechanisms that greatly favors trade efficien...