Harmony confirmed an exploit after an attacker minted 4B ONE tokens via empty blocks. ONE fell 34%, with most minted supply already on exchanges
An attacker minted 4 billion ONE tokens on the Harmony blockchain without authorization, the project confirmed on Aug. 12. Harmony said it is working with its team and relevant exchanges to stop and freeze the funds, and that it is developing a patch while evaluating rollback options.
The incident came to light after X user Juiceberg posted about the exploit earlier the same day. According to Juiceberg, the attacker used empty blocks to mint the tokens. The chain's total supply endpoint did not immediately reflect the added tokens, which may have delayed detection.
ONE fell 34% in the 24 hours following the disclosure. The token was trading at around $0.0008 at the time, placing the current market value of the 4 billion minted tokens at roughly $3.2 million.
Most of the Minted Supply Has Reached Exchanges
Juiceberg estimated that approximately 115 million ONE, about 2.9% of the minted total, remained on-chain when they posted. The rest had already been moved to exchanges, where it had either been sold or was sitting in deposit wallets ready for sale. Harmony confirmed Juiceberg's account in its own X post and said the investigation is ongoing. The blockchain has not yet disclosed the technical root cause of the exploit, and The Block reached out to Harmony for further comment.
Harmony Has Faced a Major Exploit Before
This is not the first serious security incident for the project. In June 2022, Harmony's Horizon cross-chain bridge was exploited for nearly $100 million. Attackers drained Ethereum (ETH) and several stablecoins from the bridge after compromising its multi-signature wallet, according to security researchers who examined the breach.
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The FBI identified the parties responsible in January 2023, attributing the 2022 attack to the Lazarus Group and APT38, both tied to North Korea. Harmony launched its mainnet in 2019 as a proof-of-stake blockchain positioned as a faster and cheaper alternative to Ethereum, with ONE serving as the network's token for transaction fees, staking, and governance.
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