On May 1, the NEAR Protocol Rainbow Bridge was attacked. The cross-chain bridge had temporarily been suspended for maintenance after detecting abnormal activities.
In a detail Publish, Alex Shevchenko, CEO of Aurora Labs, revealed that the attack was stopped automatically because the architecture of the bridge was designed to withstand such events. No funds were lost during the event, Shevchenko added.
The Attack
It all started when the attacker sent some ETH through the popular coin mixer, Tornado Cash, on May 1. They deployed a contract meant to deposit some funds to become a valid Rainbow Bridge relayer.
The main intention was to send blocks of “manufactured” thin clients. According to Shevchenko, the bridge watchdogs identified that the submitted block was not in the NEAR blockchain and, in turn, created a “challenge transaction” and sent it to Ethereum.
After the watchdog transaction failed, MEV bots figured that front-running it would result in a 2.5 ETH gain. The exec explained,
“As a result, the watchdog transaction failed, the MEV bot transaction succeeded and canceled the attacker’s fabricated block. A few minutes later, our relay submitted a new block. A little later, we We started investigating the strange behavior and paused all the connectors, and once we figured out the details, re-established them.
He then revealed that the attack was mitigated fully automatically, and the users continued their transactions in both directions. Shevchenko also noted that the NEAR protocol will take additional measures to ensure the cost of an attack attempt is increased – meaning – the stake for the relayer is expected to rise manyfold, so similar endeavors would cost much more. The focus should be on security and robustness, explained the CEO.
“I wish everyone innovating in blockchain to pay enough attention to the security and robustness of their products by all available means: automatic systems, notifications, bug bounties, internal and external audits.”
DeFi Bridge Attacks
In recent months, blockchain bridges have become prime targets for attacks. In one of the biggest heists in the history of cryptocurrency, attackers managed to steal $620 million worth of Ethereum and USDC stablecoin from Axie Infinity’s Ronin Network after targetting Ronin Bridge, which allows users to move funds between the network and Ethereum.
Earlier this year, Qubit Bridge lost $80 million in cryptocurrency, while Wormhole Bridge lost $320 million a few weeks later.
