They Took $320 Million In Bitcoin — Then Left A Note: “We Are Whitehats”

The Liquid Network said Sunday that purported white-hat hackers withdrew about 4,000 bitcoin, worth about $320 million, from the federation wallet that backs L-BTC. Bridge nodes were disabled, and the sidechain was paused. Other issued assets, including USDT, DePix and RWAs, were unaffected, the official account said on X.

The Liquid Network is a federated sidechain of Bitcoin, founded by Adam Back’s Blockstream. The Liquid chain issues a variety of assets such as LBTC, which it backs with BTC on the Bitcoin main chain, held in a large multisig of 15 corporate and known members. 11 of the 15 members need to sign a valid multi-signature transaction to move coins from the treasury. Before the hack, the treasury held over 4200 BTC; after the hack, Blockstream’s proof of reserves page reports a little over 207 BTC left. 

The hackers withdrew 4,019.4 BTC from the reserve address in a peg-out transaction using the SideSwap Peg-out Authorization Key. SideWap is a bridge exchange and a member of the Liquid Federation. While details on the mechanism of the hack are not confirmed yet, it appears an inflation bug on the LBTC side chain was exploited by the hackers to create over 4,000 LBTC that did not exist before, and cash them out for on-chain bitcoin from the federation. Because the transaction appeared as valid, given the consensus bug, the federation members’ HSM security servers signed the BTC withdrawal transaction, worth roughly 320 million at the time.