Bitcoin Cash gets 51% Attacked by Just Two Miners to Reverse Transaction, Price is Unchanged

• Btc.com and BTC.top carries out a 51% attack on Bitcoin Cash network to stop an unknown miner
• BTC price down less than one percent only

Two of the Bitcoin Cash miners reportedly carried out a 51% attack on the Bitcoin Cash (BCH) blockchain in an effort to reverse another miner’s transactions, per the Tweet by Cryptoconomy Podcast host, Guy Swann on May 24th.

A 51% attack occurs when someone controls the majority of the mining power on a Proof-of-Work (PoW) blockchain network. This means the majority of the block verifiers can prevent others from mining and reverse transactions.

Controlling 50 percent of the Hash Power

Typically, it has been assumed that a 51 percent attack is carried out with malicious intent, however, this isn’t the case with Bitcoin Cash. Here, two mining pools – BTC.com and BTC.top carried out this move to stop an unknown miner from taking some coins, due to a code update. Instead of rewarding the attackers or have them for themselves, this move was for the good of the community.

Swann explained, “Since the original split in 2017, there has been a significant number of coins accidentally sent to ‘anyone can spend’ addresses (due to [transaction] compatibility of signs, but no #SegWit on #BCH), or possibly they’ve been replayed from #Bitcoin onto the #BCH network.”

The attacker that day took advantage of a bug that was unrelated to the upgrade – which was subsequently patched – that caused the Bitcoin Cash network to split and BTC.top to mine empty blocks while the bad transactions made blocks impossible to produce.

“When the unknown miner tried to take the coins themselves, [BTC.top and BTC.com] saw & immediately decided to re-organize and remove these [transactions], in favor of their own [transactions], spending the same P2SH coins, [and] many others,” Swann further said.

At one point, BTC.top controlled over 50 percent of the power by itself. However, BTC.com and BTC.top were able to join together in order to reverse the blocks of transactions. Currently, both the mining pools have a combined hash power of more than 42 percent, as per the data provided by Coin Dance.

A Good or Bad Thing?

The Bitcoin Cash community is divided on this. While some developers are quiet, others like jtoomim called it “justice” and “punishment” for “antisocial behaviour.”

Meanwhile, some like Bitcoin Cash developer that goes by the name, Kiarahpromises argues that it is bad for the blockchain and shows that BCH blockchain is centralized.

“To coordinate a reorg to revert unknown’s transactions. This is a 51% attack. The absolutely worst attack possible. It’s there in the whitepaper. What about (miner and developer) decentralized and uncensorable cash? Only when convenient?” said  Kiarahpromises.

https://twitter.com/WhalePanda/status/1131979967858905088

This is certainly a matter of concern shared across proof-of-work networks. If we take a look at the bitcoin’s hashing power, according to Blockahin.com, it is divided among three mining pools only.

Currently, this attack has no effect on the price of BCH/USD as it trades at $414 with 24-hours loss of a mere 0.65 percent. BCH is up 161 percent till date, in 2019.