An attack on the Ethereum blockchain early Tuesday morning temporarily redirected a small percentage of network nodes to a non-canonical chain.
According to Ethereum researcher and Go Ethereum software developer Marius Van der Weyden, the main Ethereum network is currently working fine and the attack is unlikely to be replicated on a larger scale. The attack was first reported by Alex S. of Flexpool on the Ethereum R&D Discord after 3 a.m. ET. “Is there something wrong with the mainnet again?” he wrote referring to a chain split that occurred online in late August.
He noted that some of his nodes write the “highest block” of the chain to a block number that technically does not exist since it was set to an amount greater than the “current block”. Researchers speculated on Discord that the reason was the peer-to-peer posting of a version of the chain with an invalid proof of work.
Van der Weyden said the attack was “experimental”.
“Someone posted an invalid chain that was rejected by the majority of customers. ~ 25% of Nethermind customers accepted the invalid chain,” wrote Van Der Weyden. “Judging by the ethernet nodes, ~ 20 nodes or 0.8% of the network were affected. I don’t think it was a targeted attack on the network, but most likely someone is experimenting and confirming their experiment on a live network.”
Tomasz Stanczak, founder of infrastructure company Ethereum Nethermind, tweeted that a public statement will be released. Van der Weyden noted that due to the nature of the attack, it is unlikely that a similar exploit could scale to a certain extent to have a significant impact on the network. Ethereum checks blocks normally. Van der Weyden also noted that customer diversity is key to the state of the network, especially as it prepares to move to a new Proof of Stake (PoS) consensus model.
“Especially with the move to proof-of-stake, customer diversity is extremely important, as a well-balanced distribution of customers greatly reduces the likelihood of an invalid chain being created,” he said.