Upbit transfers 99% of assets to cold wallets after major hack

• Upbit transferred 99% of customer funds to cold wallets after a major hack of Solana’s hot wallet.
• The company will compensate users for direct losses and upgrade its asset storage system.

South Korea’s largest crypto exchange, Upbit, has almost completely transferred customer assets to cold storage after a major hack of the Solana hot wallet.

Operator Dunamu said that 99% of user funds will now be stored offline, and the volume of hot wallets will be reduced to almost zero. This decision was made after hackers stole 44,5 billion won (about $30 million).

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These changes significantly exceed the requirements of South Korea’s Virtual Asset Protection Act, which requires exchanges to keep at least 80% of customer deposits in cold wallets.

Upbit reduces use of hot wallets

Cold wallets are offline, making them more difficult to hack, but transactions are slower. Hot wallets are more convenient, but they are more often targeted by hackers. For traders, the transition to 99% cold storage means that if there is another hack, significantly less will be at risk.

According to Dunamu, at the end of October 2025, Upbit stored 98,33% of customer assets in cold wallets and 1,67% in hot wallets. Even before the attack, this was the lowest hot storage rate among Korean exchanges: competitors had 82–90%.

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The company maintained a cold wallet share above 98% despite rising cryptocurrency prices and an influx of funds from new listings. Upbit has now completed the review and upgrade of its infrastructure and intends to completely abandon hot wallets.

The attack on Solana’s assets accelerated the adoption of these measures. Initially, the damage was estimated at 54 billion won (about $36 million), but later the amount was revised to 44,5 billion. Direct losses to users amounted to 38,6 billion won ($26,2 million), and the company promised to fully compensate them from its own reserves.

Experts identified a vulnerability that could have allowed attackers to gain access to private keys by analyzing blockchain data. Upbit has not confirmed whether this vulnerability was exploited, but the very fact that it was identified highlighted the systemic risk of hot wallets.