Upbit, the biggest South Korean crypto exchange, suffered a massive hacking attack on Thursday worth 54 billion won, or 36-point-nine million U.S. dollars.

Upbit’s operator Dunamu notified customers of the hack at 12:33 p.m., following a press conference held on the merger between Dunamu and Naver Financial.

Oh Kyung-seok, the chief executive officer of Dunamu, said a portion of Solana-affiliated assets worth approximately 54 billion won was confirmed to have been transferred to an unauthorized wallet address at 4:42 a.m.

Oh said they plan to cover the full amount lost with Upbit assets to prevent any damage to customers’ assets.

Dunamu has temporarily suspended virtual asset deposit and withdrawal services as a follow-up measure and is conducting an overall security check.

Financial authorities are planning to carry out an on-site inspection immediately to assess the situation.

This is the first major hacking incident at Upbit in six years, after 340-thousand Ethereum tokens worth 58 billion won were stolen in November 2019.