Hassan Maishera
TL;DR
-
Symbiosis recovered approximately 15 BTC following a September 11 exploit targeting its native Bitcoin Bridge.
-
Blockaid said the attacker minted approximately 46.1 billion unbacked syBTC through the BridgeV2 contract.
-
The attacker reportedly converted only 4.39 WBTC, generating an estimated $336,000 in proceeds.
-
Symbiosis offered a 20% bounty for the return of funds and is preparing a compensation framework for affected liquidity providers.
Cross-chain liquidity protocol Symbiosis has recovered approximately 15 BTC following an exploit targeting its native Bitcoin Bridge.
The recovered Bitcoin, worth about $1.15 million at current prices, is being held in a multisignature wallet controlled by the Symbiosis team.
The protocol has offered the attacker a white-hat bounty equal to 20% of the funds in exchange for returning the remaining assets.
Symbiosis Pauses Native Bitcoin Bridge
The exploit occurred on September 11 after an attacker discovered a vulnerability in the Symbiosis Bitcoin Bridge. The protocol has not released technical details about the flaw.
Following the incident, Symbiosis halted its native Bitcoin routes and isolated the compromised bridge from the rest of its infrastructure. Its routes across Ethereum Virtual Machine networks, TRON, and TON remained available, while its Octopools product and relayer network continued operating.
Symbiosis has since restored Bitcoin swaps through third-party partners Chainflip and THORChain. However, the protocol’s native Bitcoin Bridge remains suspended while the investigation continues.
The project said it is contacting each affected liquidity provider directly and developing a compensation framework. Eligibility requirements and other details are expected to be released later.
Attacker Offered 20% White-Hat Bounty
Symbiosis initially gave the attacker until September 13 to claim a bounty worth 20% of the recovered funds.
After the deadline, the protocol said it would make the same reward available to anyone who provides information leading to the recovery of additional assets.
The offer is intended to encourage either the attacker or outside investigators to assist with the recovery process. Symbiosis did not immediately provide additional comments about the incident.
Blockchain security firm Blockaid reported that the exploit involved a call to Symbiosis’ BridgeV2 contract on BNB Chain. The transaction allegedly created approximately 46.1 billion unbacked syBTC and transferred the tokens to a newly created address.
That amount is more than 2,000 times Bitcoin’s maximum supply of 21 million coins. However, the attacker was reportedly able to convert only around 4.39 Wrapped Bitcoin through Uniswap v4 on Ethereum, generating approximately $336,000.
DeFiLlama has classified the incident as an unbacked cross-chain mint and also estimated the realized loss at $336,000. This highlights the difference between the theoretical value of fraudulently created tokens and the liquidity an attacker can actually extract.
Bridge Exploits Continue to Target Wrapped Assets
The Symbiosis attack follows a similar incident involving Blockstream’s Liquid Network, where an attacker created approximately 4,000 unbacked LBTC and redeemed the tokens for Bitcoin.
About 3,400 BTC was subsequently returned, although roughly 598.5 BTC remained outstanding. Blockstream rejected the attacker’s demand for a bounty on the unrecovered funds.
In April, an attacker also exploited Polkadot-focused Hyperbridge to mint one billion bridged DOT. Despite the enormous number of unauthorized tokens, the attacker extracted only approximately $237,000.
Symbiosis says it has processed more than $10 billion in transactions since launching around five years ago. DeFiLlama data places the protocol’s current total value locked at roughly $7 million, with cumulative bridge volume of approximately $3.19 billion.
