Symbiosis Protocol reported the return of approximately 15 Bitcoin that were at risk after an attack by an unknown perpetrator on September 11. The project team stated that they were able to isolate the funds related to the bridge’s collateral, and they are now on a cryptocurrency wallet under their control.
Symbiosis Protocol is a DeFi protocol for cross-chain swaps and liquidity. It helps facilitate swaps between different blockchains via crypto bridges; in such a scheme, collateral, the issuance of synthetic assets like syBTC, and control of funds in the bridge are especially important.
How the Attacker Exploited the Vulnerability
The attack affected the BridgeV2 smart contract. According to Symbiosis, the vulnerability allowed the issuance of a large volume of unsecured synthetic syBTC tokens. Their nominal value was calculated in the billions of dollars, but the actual damage turned out to be significantly lower than initial estimates.
The developers managed to separate about 15 BTC that were held as bridge collateral. This helped limit the consequences for the cross-chain liquidity protocol and its ecosystem, where stable market liquidity, secure swaps (finance), and proper operation of infrastructure between blockchain networks are important.
Actual Losses Were Lower Than Expected
The attacker was able to swap about 4.39 WBTC through Uniswap v4. The value of these assets was estimated at approximately $336,000. Compared to the volume of syBTC issued, this amount was significantly less than the potential damage suggested by the first data after the attack.
For the decentralized finance segment, such incidents are especially sensitive: a single problematic contract can affect not only a specific asset but also trust in the connections between networks, including solutions that work with Bitcoin, stablecoins, and other tokens. In such systems, the security of the bridge, correct fee calculation, and control over the issuance of synthetic assets are all important.
“We are in direct contact with all affected partners under license agreements. We are developing a compensation system and will soon publish the criteria,” the Symbiosis team stated.
The Project Offered a Reward for Assistance
Symbiosis also announced a reward of 20% of the amount to anyone who provides information that can help recover the remaining assets. The team continues to work with affected partners and is preparing a compensation mechanism.
Previously, another high-profile episode occurred with the Liquid network wallet: after about 4,000 Bitcoin worth approximately $320 million were withdrawn, hackers returned 3,400 Bitcoin, valued at about $270 million. This was reported by JAN3 CEO and former Blockstream top manager Samson Mow.
The Symbiosis incident once again showed how critical bridge security is in DeFi infrastructure, especially when protocols interact with different networks, including Solana, Bitcoin, and other major areas of the crypto market.
