A notice from the firm, one of the world’s largest digital currency exchanges, claimed that the attack began last night and was discovered this morning, with around 35bn won ($31.5m) taken.
The firm has halted deposits and withdrawals “for the time being” while it conducts a thorough review into what happened.
It claimed that all lost funds will be covered by Bithumb from its own reserve and that remaining assets were removed to a secure cold wallet.