Symbiosis Reels from Massive Fake Bitcoin Heist

On September 11th at approximately 04:28 UTC, an attacker exploited the Bitcoin Bridge of cross-chain protocol Symbiosis, minting a massive amount of fake Bitcoin. The attacker created around 2^62 raw units of syBTC, a synthetic representation of Bitcoin, and sold some of it on BNB Chain for a profit of roughly $336,000 in WBTC.

The vulnerability only affected the native Bitcoin Bridge, leaving other routes and components operational, including EVM chains, TRON, TON, and the relayer group. Symbiosis has recovered approximately 15 BTC ($76,863) from the attacker, which is currently secured in a team-controlled multisig.

The protocol has not announced the return of the affected bridge and instead offered users alternative Bitcoin routes through partners Chainflip and THORChain. The distinction between partner-routed swaps and native Symbiosis Bitcoin Bridge swaps remains, keeping traffic off the paused bridge while users access other options.