Reports said that the Horizon Bridge to the Harmony layer-1 blockchain has been exploited for $100 million in altcoins which are being swapped for Ether (ETH).
It has been reported that the hack may vindicate previously raised community concerns about the robustness of the two of four multisig that reportedly secures the bridge.
However, starting at about 7:08 am EST until 7:26 am EST, 11 transactions were made from the bridge for various tokens. They have since begun sending tokens to a different wallet to swap for ETH on the Uniswap decentralized exchange (DEX), then sending the ETH back to the original wallet.
The report said that Frax (FRAX), Wrapped Ether (wETH). Aave (AAVE), SushiSwap (SUSHI), Frax Share (FXS), AAG (AAG), Binance USD (BUSD), Dai (DAI), Tether (USDT), Wrapped BTC (wBTC), and USD Coin (USDC) have been stolen from the bridge through this exploit. The Horizon Bridge facilitates token transfers between Harmony and the Ethereum network, Binance Chain and Bitcoin.
Likewise, Harmony, the operator of the bridge, announced late on Thursday that the bridge has been halted. It said the BTC bridge and its assets have not been affected by the attack. The Harmony team also said it was working with “national authorities and forensic specialists” to determine who was responsible. A post-mortem is sure to follow.
Harmony is a layer-1 blockchain using proof-of-stake (PoS) consensus. Its native token is ONE. Concerns have previously been expressed as to the soundness of Horizon’s multisig wallet on Ethereum, which only required two out of the four signees to drain the funds.
A founder of Chainstride Capital crypto-focused venture fund Ape Dev noted on Twitter on April 2 that the low number of required signers would leave the bridge open for “another 9 figure hack.”
Thus, Vitalik Buterin discussed the issues with token bridges in a Reddit post this January. He posted that when bridges get exploited, it threatens the liquidity of each chain affected. He added that as the amount of token bridges increases, the threat of a 51% attack on one chain could present a greater contagion risk to others.