Ethereum blockchain overcame the intentional attack on 31st Dec 2019. This attack came so close that it was about to take down the whole Ethereum network.

The attack was confirmed by an Australia-based blockchain developer Liam Aharon. He said that the attack affected Parity. He says Ethereum needs more clients in order to survive further attacks in the future.

A crypto security consultant also noticed this attack and gave details about the attack. He said:

The attack is simple: you send to a Parity node a block with invalid transactions, but valid header (borrowed from another block). The node will mark the block header as invalid and ban this block header forever but the header is still valid.

Aharon stated that a bug in the Parity client was exploited during the attack. He also pointed out that several Parity ETH nodes were made unsynced with the Ethereum network. However, after the attack was confirmed, the Ethereum network released a software patch.

A distributed systems expert named George Pîrlea also commented on the attack and elaborated the attack in the following words:

The attack consists of sending a block along with a header that doesn’t match the block. Parity verified the block, noticed it did not match the header, and then marked the *header* as bad. This means the real/correct body would never be downloaded.

Aharon further added that the intentional attack could not take down the entire Ethereum network. The reason is that it has got another Ethereum client known as Geth. It has the ability to survive the attack. He says that if Ethereum would not have Geth then the attack could have brought down the whole Ethereum network.

Parity announced that it plans to withdraw support for the clients. Aharon says that with fewer resources supporting Parity, Ethereum would only have Geth. He says with only one Client Ethereum network could be affected. And it can face more attacks in the future.