Japanese cryptocurrency exchange DMM has suffered a significant security breach, resulting in the loss of over $305 million worth of Bitcoin on May 30. The exchange confirmed the hack on its website and assured users that all deposits would be “fully guaranteed.”
In response to the breach, DMM has temporarily suspended withdrawals, new account registrations, new spot buy orders, and all new leveraged orders. However, existing limit orders will remain unaffected.
The cyber attack first came to light on social media platform X at 10:14 pm UTC on May 30. Analytics platform Whale Alert posted a message stating, “4,502 #BTC (308,948,771 USD) transferred from unknown wallet to unknown new wallet.” The post linked to blockchain data showing an outflow of 4,502.9 BTC, equivalent to $305 million at current prices, from a single wallet.
Initially, Whale Alert identified the wallet’s owner as “unknown.” Later, DMM confirmed that it lost precisely 4,502 BTC in the attack, indicating it was the source of this large transaction.
DMM stated it has already implemented measures to prevent further unauthorized access and will “procure the equivalent amount of BTC” to ensure that all users are compensated. These funds will be sourced “with support from our group companies.”
The exchange urged users to stay updated through its website, promising to post a new alert once all services are back to normal.
DMM exchange, owned by the e-commerce giant DMM Group, has been operational since January 2018. The company also operates a cryptocurrency mining firm.
This incident underscores the ongoing risks associated with cryptocurrency exchanges. In November, Poloniex lost over $100 million in a similar attack, and in April 2023, GDAC suffered $14 million in losses due to a hack.