Miners Carry Out 51% Attack on BCH Blockchain

Guy Swann, the host of Cryptoconomy Podcast, tweeted on May 24 that two miners executed a 51% attack on Bitcoin Cash’s (BCH’s) blockchain. According to the tweets, this attack was carried out in an effort to reverse transactions carried out by another BCH miner.

A 51% attack takes place when a majority of the mining power called hash rate on a PoW (Proof-of-Work) is controlled by one entity or a single group of entities, who can then prevent others from mining and can even reverse transactions.

Taking Advantage of the BCH Hard Fork

This 51% attack is a direct result of the hard fork that took place on the BCH network on May 15. During that network upgrade, an unknown miner took advantage of a vulnerability, which added invalid transactions to the Mempool (the pool of unprocessed transactions).

Basically, because of that bug in the BCH system, the network split and some miners were processing empty (invalid) blocks for a short period of time, and others were unable to unable to participate in the mining process at all.

According to one source, these transactions were actually poison, and the BCH network was crippled for more than 1.5 hours. In that time period, the unknown miner tried to take coins that they would not otherwise have had access to.

Two miners, BTC.top and BTC.com, realized that someone was trying to take advantage of the bug and teamed up to carry out the 51% attack. The two miners used this method for the good of the BCH community, rather than for a malicious attack. By taking over the BCH network, they tried to undo what this unknown miner had done.

BTC.top did not have enough mining power to carry out the 51% attack on its own, which is why it teamed up with another miner, BTC.com. Together, they had a 43% control of the BCH mining pool, however, due to the fact that most miner at that time were locked out, they were able to take control of the network and correct what the attacker did.

Controversial Move

While many in the community lauded what BTC.top and BTC.com did, others raised concerns about their actions, stating that such steps were a bad sign for the BCH network. They argued that this event demonstrated that the altcoin was too centralized.

According to Swann, this act killed perceptions that Bitcoin Cash was decentralized and censorship resistant.