Cross-chain liquidity protocol Symbiosis was exploited on September 11 after an attacker used signed BridgeV2 transactions to mint a large quantity of syBTC, a synthetic Bitcoin token. Blockaid said roughly 2^62 raw syBTC units, described as about 46.1 billion tokens with eight decimal places, were sent to a newly created account on BNB Smart Chain. DefraudTG separately estimated about 368.9 billion syBTC was minted across Ethereum and BNB Chain through eight bridge transactions. The attacker sold about 4.39 WBTC through Uniswap V4 on Ethereum, generating roughly $336,000, while about 184.5 billion syBTC remained on BNB Chain. Symbosis said it was working with security researchers and that non-BTC routes, ETH pools and stablecoin pools were unaffected.