After the Bitcoin bridge was attacked on September 11th, the cross-chain liquidity protocol Symbiosis has recovered approximately 15 BTC and transferred the related funds to a multi-signature wallet under the team's control. The protocol has not yet announced the final amount of losses, stating that it is still calculating the affected assets and contacting each relevant liquidity provider one by one.

15 BTC were recovered after the attack.

Symbiosis indicates that this incident only affects its native Bitcoin bridge. Therefore, the native BTC routing has been suspended, and the affected bridging modules have been isolated from other infrastructure. Other routes involving the EVM network, TRON, and TON are still in operation, and the Octopools products and relay networks have not been taken offline either.

During the suspension of the native Bitcoin bridge, users can still complete Bitcoin exchanges through Chainflip and THORChain. The recovery time for the native bridge has not yet been announced; it is only stated that they are collaborating with security researchers to assess the final impact of the incident.

Unpledged syBTC minted up to 46.1 billion coins

Blockchain security company Blockaid stated that after attackers invoked the BridgeV2 contract of Symbiosis on BNB Chain, they minted approximately 46.1 billion syBTC tokens without any asset backing and sent them to newly created addresses. This number far exceeds Bitcoin's fixed cap of 21 million tokens, but these tokens are synthetic assets generated by the affected bridge contracts and do not represent an increase in the total BTC on the Bitcoin network.

However, the actual amount that the attackers were able to cash out was significantly less than the number of coins they minted. Blockaid indicates that the relevant addresses sold approximately 4.39 WBTC coins on Ethereum through Uniswap and v4, earning about $336,000. DeFiLlama also classified this incident as “unpledged cross-chain coin minting,” with a recorded loss of around $336,000.

• Unpledged mint quantity: approximately 46.1 billion syBTC
• Actual selling volume: approximately 4.39 WBTC
• Recorded losses: approximately $336,000

LP The compensation plan is still being formulated.

Symbiosis previously offered a white-hat solution to the attackers: if they returned the remaining funds by September 13th, they could receive a reward of 20% of the amount recovered. After the deadline, it was stated in the agreement that this 20% reward would be given to anyone who could provide clues or help continue to recover the assets.

The market's focus has now shifted to liquidity providers affected by Bitcoin routing. Symbiosis indicates that the team is directly contacting all affected LP, and a compensation framework is being prepared, with the specific application criteria to be announced separately.

Additional information:Recently, in multiple cross-chain bridge attacks, there has been a situation where the "minting volume is large, but the actual cash-out amount is limited." A few days ago, in the Liquid Network incident, approximately 3,400 BTC were returned; in April of this year, in the Hyperbridge incident, the attacker ultimately withdrew about $237,000.