Two Miners Stage 51% Attack on Bitcoin Cash Network to Reverse Attacker’s Transactions
Two mining pools on the bitcoin cash (BCH) network recently used 51% attack to reverse the transactions of another miner on the blockchain.
BTC.com and BTC.top carried out the attack on an unknown miner after a bug interfered with the bitcoin cash network during a hard fork and allowed the attacker to access coins they didn’t deserve.
The bug (which has since been patched) split the BCH network and caused the mining of empty blocks.
51% attacks occur when a single miner (or group of miners) controls the simple majority of a network’s total hash rate. With this power, the miners can execute transactions like rewriting a network’s transaction history.
It is generally thought that a 51% attack on a more mature network would be difficult to execute, especially as these coins are heavily-mined.
But unlike Bitcoin (BTC) most of the small cryptocurrencies have an unstable network, which increases the possibility that one miner can acquire the majority of the hashrate and attack.
In January, Ethereum Classic reportedly suffered a 51% attack and Bitcoin Cash came dangerously close to one when BTC.top amassed over 50 percent of the network’s hashrate.
In the case of the two miners, BTC.com and BTC.top allegedly combined their hash rates to be able to reverse the transactions of the attacker. Coin Dance shows that the two mining pools have a current combined hash power of 44%.
Not everyone agrees that it was the right thing to do, with some arguing that coordinating a “reorg” to revert the transactions of an unknown attacker beats the whitepaper. One user called it the “absolute worst attack possible.”
Some say it reveals how Bitcoin Cash is actually very centralized, with Blockchain.com showing that just three miners share half of the hashing power on the bitcoin cash network.
Others questioned BTC.com and BTC.top’s moves saying they basically did what the attacker had done- taken the coins for themselves.
Guy Swann, a bitcoin podcast host wrote on Twitter that a code change allowed coins that were sent to “‘anyone can spend’ addresses” to become spendable. That is what the unknown attacker decided to do- take the coins for themselves.
Swann says BTC.top and BTC.com saw this and swooped, joining forces to reverse the attacker’s transactions. The mining pools “decided to re-organize and remove” the attacker’s transactions but in so doing, favored themselves.
According to him, BTC.top and BTC.com ended up “spending the same P2SH coins,” they allegedly swooped to revert.
Some BCH users maintain that the 51% attack by the two miners was the right course of action. One supporter, Jonathan Silverblood noted that although unfortunate, the development exemplified proof of work mining.
Disclaimer: This is not investment advice. Cryptocurrencies are highly volatile assets and are very risky investments. Do your research and consult an investment professional before investing. Never invest more than you can afford to lose. Never borrow money to invest in cryptocurrencies.