The incident occurred on September 12, and preliminary assessment indicated that the unauthorised transactions involved Ethereum ($ETH), Tron ($TRON), and Polygon ($MATIC) cryptocurrency. 

"On September 12, 2023, our Risk Control System detected anomalous withdrawals from several hot wallet addresses used to store CoinEx's exchange assets. Promptly recognising the gravity of the situation, we immediately established a special investigative team to delve into the matter," CoinEx Global wrote on X (formerly Twitter). 

"The precise amount of the loss is still being determined, and the affected fund is just a very small portion of CoinEx's total asset," it added. 

While CoinEx has not provided any information about the financial impact incurred because the investigation is still ongoing, a more recent estimate on the CoinEx losses from 'CertiK Alert' raises the figure to $53 million. 

"The @coinexcom exploit losses have now reached an estimated $53 million taking the total losses for private key compromises this year to $377.7 million," CertiK Alert posted on X. 

Moreover, the cryptocurrency firm said that the affected users will receive full compensation for any loss due to this breach. 
"Affected parties will receive 100 per cent compensation for any loss due to this breach. For added security, deposit & withdrawal services are temporarily suspended and will resume after a thorough review," CoinEx said. 

However, it's not confirmed who hacked the CoinEx server and stole from them, but blockchain investigator ZachXBT believes that the North Korean state-backed group 'Lazarus' is responsible for this breach. 

"It appears North Korea is also responsible for the $54M @coinexcom hack from yesterday after they accidentally connected their address to the $41M Stake hack on OP & Polygon," ZachXBT said. 

The threat group was linked to the theft of $35 million from Atomic Wallet in June, $60 million from Alphapo and $37.3 million from CoinsPaid in July.