2020 isn’t going so great for the popular Bitcoin Hardfork Bitcoin Gold (BTG). In less than seven months’ time, the network has undergone two 51% attacks. The latest attack was executed on July 10, but reports state that the cryptocurrency’s development managed to prevent the attack.
A 51% attack refers to an attack on a blockchain network when more than 50% of the network’s hashrate is controlled by a group of miners or a single organization, potentially allowing the attackers to halt payments between some or all users.
Attackers are also able to reverse transactions that were completed during their control over the network, thus allowing them to double-spend coins.
Bitcoin Gold, which runs on a modified Proof-of-Work (PoW) mining algorithm called Equihash, underwent a similar attack recently according to an “Emergency update 0.17.2” notice posted on the cryptocurrency’s website.
While the attackers ultimately released a long chain of over 1300 blocks that they were mining since July 1, the BTG network wasn’t affected by the attack as the developer team “detected this illicit activity early on and sent alerts to pools and exchanges to protect them.”
Prior to the attack, all Bitcoin Gold mining pools and centralized crypto exchanges that support BTG had updated to version 0.17.2, which is immune to this attack due to a “checkpoint included at block 640650, hash 000000059ec8884fa4fbbdbe46c09cfb4ecba281dfa2351a05084e817c1200ae from July 2 at 2 am UTC, mined by MiningPoolHub, a known honest block.”
As a result, the attacker failed to take over the network as the “information was not public” and the attacker continued to mine their chain for 10 days using rented hash power from NiceHash, and released its chain of 1300+ blocks on July 10.
Luckily, the said checkpoint was after the attacking blocks mined on July 1st, and the pools and exchanges on the honest chain, running the updated version of Bitcoin Gold, “automatically rejected the attacker’s chain.”
As of now, users are advised to upgrade their BTG Core full nodes to version 0.17.2
History repeats for Bitcoin Gold
This was the second time the BTG network was attacked this year. As The Daily Chain had reported, the network suffered heavy losses due to two deep reorganizations, which caused the double-spending.
The attackers first netted 1,900 BTG ($19,000), and the second roughly 5,267 BTG ($53,000), summing up to total losses worth $72,000.However, this wasn’t the network’s biggest losses.
The network underwent its first 51% attack back in 2018 and the attackers managed to get away with 388,201 BTG, worth $17.5 million at that time.