Yesterday, Tuesday 14th September 2021, saw an attack on the Ethereum blockchain that temporarily diverted 0.8% of the network’s nodes to a non-canonical chain. While this is an almost insignificant amount when you compare it to the 54% of nodes affected by a bug only two weeks ago, it is another blow for the blockchain.
Alex S from Flexpool questioned if there was an issue with the mainnet around 3 AM Eastern time yesterday after spotting that his nodes were recording numbers that simply did not exist.
What Happened to the Ethereum Nodes?
While it is almost impossible to understand the reasoning behind the attack, there is speculation that it was an experimental attack. Ethereum developer Marius Van Der Wijden Tweeted the following:
“Someone unsuccessfully tried to attack #ethereum today by publishing a long (~550) blocks which contained invalid pow’s. Only a small percentage of @nethermindeth nodes switched to this invalid chain. All other clients rejected the long sidechain as invalid.”
Who did the Attack Affect?
It appears that the attack affected Nethermind, an Ethereum infrastructure company, and that ~25% of their clients had accepted the invalid chain.
However, even though most (if not all) of the nodes concerned were from Nethermind, Marius said that he didn’t think the attack was aimed at Nethermind specifically and that the attacker was “probably experimenting on the live network.”
Could This Happen Again?
Van Der Wijden has stated that everything is back to normal now and that this type of attack is unlikely to happen at any greater scale, and that it is unlikely to have and major impact on the network.
Furthermore, Marius told CoinDesk:
“A diversity of clients is key for the health of the network, particularly as it prepares for a transition to a new proof-of-stake consensus model.
“Especially with the switch to proof-of-stake, client diversity is extremely important as a well-balanced distribution of clients greatly decreases the probability of creating an invalid chain.”
Only time will tell if this sort of attack will become more common in the future. However, we can hope that the move to PoS will help.