Gatecoin Hack

Between late on May 9 and the evening of May 12, 2016 (Hong Kong time), an attacker stole 185,000 ETH and 250 BTC from Hong Kong exchange Gatecoin. The loss was worth about $2 million, roughly 15% of all crypto deposits on the exchange. Gatecoin said most client crypto was kept in multi-signature cold wallets and that hot wallets were capped at 5% of holdings. The attacker changed Gatecoin's system so that incoming ETH and BTC deposits skipped the multi-sig cold storage and landed in the hot wallet, which is how losses went past that cap. Gatecoin linked the breach to a server reboot on May 9 and suspected a man-in-the-middle attack, but has not published a full technical cause.

Gatecoin found the suspicious transactions on May 13 and suspended all services. It said its DGD, REP and DAO token holdings and segregated fiat funds were safe, planned a withdrawal platform for late May, and said it was trying to raise funds to cover the BTC and ETH losses. By March 2019 the company was in liquidation, with Hong Kong firm Borrelli Walsh appointed to identify and realize its assets.