Bitcoin's fork project Bitcoin Gold announced a double-spend attack. According to official disclosures, BTG suffered two 51% hashrate attacks last week, and two recharge transactions on the exchange were cancelled, involving about 1900 BTG and 5,267 BTG, close to $ 90,000, but it is currently unknown whether the exchange has suffered losses in the attack. By analyzing the hash power data, Bitcoin Gold officially believes that the hash power used by the attackers comes from the hash market NichHash. Bitcoin Gold has now contacted the exchange and will provide security assistance. In addition, BitGold said that it has been developing a new type of decentralized consensus algorithm against 51% attacks since last year, and plans to release it in the first quarter of this year. Bitcoin Gold suffered a 51% attack in 2018.A malicious miner gained 51% of the computing power of the Bitcoin Gold network and stole more than 380,000 BTGs, valued at approximately $ 18.6 million.