Japanese exchange Zaif lost approximately $60M worth of Bitcoin, Bitcoin Cash, and MONA tokens via hot wallet compromise.
Zaif's hot wallet servers were breached for approximately 2 hours on September 14, 2018. The attackers exploited unauthorized access to drain Bitcoin, Bitcoin Cash, and MONA tokens. The breach was not discovered for several days. Zaif's operator Tech Bureau later sold a majority stake to Fisco to compensate user losses.
Bitcoin and BCH funds moved through multiple wallets and OTC desks. Fisco acquired Tech Bureau and compensated users approximately $44.5M in fiat, with remaining losses covered by asset sales. The attackers were never publicly identified. Japan's FSA issued a business improvement order to Tech Bureau.