Crypto exchange Coinsbuy loses $8 million in coordinated two-blockchain attack

Crypto exchange Coinsbuy lost more than $8 million in a coordinated attack across TRON and Ethereum on Aug. 9, according to onchain data reviewed by blockchain security researchers.

The attacker began with a 5 USDT transaction before draining eight TRON wallets of 6.04 million of the dollar-pegged stablecoin in about an hour. On Ethereum, three wallets were simultaneously emptied of 1.89 million USDT and 77 ETH, which was swapped to ETH via 1inch through a wallet created the same day.

Onchain records show the two chains were linked through cross-chain swapper Bridgers, whose Ethereum payout contract sent funds directly into the Ethereum swap wallet, connecting what appeared to be separate operations into a single incident.

The attacker routed some 79% of the stolen funds through instant exchange FixedFloat using roughly 50 single-use addresses. ChangeNOW separately froze a six-figure sum after being contacted by Specter Investigations.

Around 282 ETH, roughly $542,000, across five addresses remains unmoved.

Within 24 hours, Coinsbuy refilled the drained wallets to within 0.05% of their pre-attack balances — behavior researchers say indicates the team does not believe private keys were compromised. The attack vector has not been established. Coinsbuy has not issued a public statement.

The incident adds to an increasingly costly year for the industry, which had already seen roughly $972 million stolen across the sector through late July.

CoinDesk has emailed Coinsbuy for comment.

Additional reporting by Ollie Acuna.