Bitcoin : Symbiosis recovers 15 BTC after the hacking of its bridge

The inter-chain liquidity protocol Symbiosis recovered about 15 BTC after a flaw targeting its Bitcoin bridge. The September 11 incident led the project to suspend its Bitcoin Bridge service and isolate the affected infrastructure. Meanwhile, Symbiosis restored bitcoin trading thanks to Chainflip and THORChain. The protocol also offers a 20% bounty to recover the remaining funds. This operation comes as several bridges have undergone a massive creation of unbacked tokens.

Symbiosis recovers part of the Bitcoin funds after the attack

According to Symbiosis, an attacker exploited a vulnerability in its bridge on September 11. The protocol, however, did not detail the nature of the attack. After the flaw, the team interrupted its native Bitcoin routes and isolated the affected bridge. The other protocol services remained operational.

Routes on the EVM, TRON, and TON networks remained operational, as did Octopools. The relay network continues to function. The protocol restored Bitcoin exchanges through Chainflip and THORChain. Its own Bitcoin Bridge remains suspended.

Symbiosis states it is working with each concerned liquidity provider. The team is preparing a compensation framework. Symbiosis controls a multisignature wallet that holds the roughly 15 BTC recovered. At the indicated time, these bitcoins represent about $1.15 million.

A bounty offered to recover the remaining funds

To accelerate asset restitution, Symbiosis offered a 20% bounty of the stolen funds. This offer was aimed at the attacker until September 13. After that date, another possibility applied. Anyone providing information enabling fund recovery could receive the same reward.

The recovered amount represents part of the assets linked to the incident. Symbiosis secured the 15 BTC found in a multisignature wallet. The protocol continues its efforts with affected providers. This coordination is intended to accompany the future compensation scheme.

The case also involves the creation of billions of unbacked syBTC tokens. Blockaid announced having detected a flaw on BNB Chain, where a call to the Symbiosis BridgeV2 contract generated about 46.1 billion syBTC. These tokens were then sent to a new address. The volume created exceeds the supply of 21 million bitcoins.

Tokens massively created, but losses more limited

Despite this considerable issuance, Blockaid indicates the suspected attacker only sold about 4.39 WBTC via Uniswap v4 on Ethereum. This operation would have earned them $336,000. DeFiLlama classified the incident as an unsecured cross-chain token creation, with a loss of $336,000. The gap between tokens created and funds extracted thus appears significant.

The Symbiosis case recalls that of Liquid, exploited less than a week earlier. A hacker then created about 4,000 unbacked LBTC before exchanging them for bitcoins held by the network. The responsible party then returned about 3,400 BTC. Blockstream however refused to pay them a bounty regarding the roughly 598.5 BTC still in circulation.

Other bridge attacks have shown a comparable divergence between theoretical issuance and realized gains. In April, an attacker exploited Hyperbridge, a bridge dedicated to Polkadot, to create 1 billion DOT. They ultimately pocketed only about $237,000, a fraction of the theoretical token value. These precedents distinguish created tokens from funds.

Symbiosis claims to have facilitated more than $10 billion in transactions since its launch about five years ago. According to DeFiLlama data, the protocol currently holds about $7 million in total value locked. Its data also show around $3.19 billion in volume on bridges. The future depends on remaining funds and measures for affected providers.

Follow-up will now focus on assets still unrecovered and on the compensation framework announced by Symbiosis. For BTC, the immediate challenge remains securing the concerned funds, while the Bitcoin Bridge service remains suspended. The next steps will assess final losses and responses to affected actors.