An increase in funds sent from illicit addresses has accelerated the rise, indicating the technology remains attractive to cyber criminals.

Flashpoint says international sanctions and a string of law enforcement actions are causing trouble for criminals to cash out.

RaidForums boasted at one point of having close to 10 billion pieces of PII for sale, making it one of the biggest destinations for cybercriminals.

Narcotics trafficking and money laundering were the main business for Hydra, which researchers say was the largest dark-web market.

Hydra has remained resilient where others have fallen to law enforcement operations.