According to James Lovejoy, a cryptocurrency researcher for the Digital Currency Startup at MIT, he has noticed that Bitcoin Gold (BTG) has experienced another 51% attack.
In its GitHub postLovejoy wrote that there were two reorganizations in the BTG blockchain with double spending (the practice of spending the same coins twice). On January 23, two blocks were removed and 13 blocks were added that allowed a double expense of $ 19,000. On January 24, a significantly larger sum ($ 53,000) was spent with 15 blocks removed and 16 blocks added.
Lovejoy suggested that the bad actor behind the reorganization successfully stole the money from his victims. The worst case scenario for the attacker was the breakeven point.
This attack never managed to obtain the same level of coverage as the previous one and went almost unnoticed. In May 2018, Fortune reported that hackers stole more than $ 17.5 million after successfully reorganizing the Bitcoin Gold blockchain and reversing confirmed transactions.
After this theft, many cryptocurrency exchanges are they moved to strengthen their security by increasing the number of confirmations required. Lovejoy is still certain that exchanges must implement more stringent confirmation requirements since the "budget constraint" for attackers remains insignificant.
Bitcoin Gold is an Equihash-based Bitcoin fork that was created in 2017 to revive GPU mining that was eclipsed by powerful ASIC miners. Although its developers claim that eradicating ASIC mining would also reduce the risk of another attack, the network remains vulnerable.
Ethereum Classic was also attacked by hostile actors in January 2019, which resulted in a theft of $ 1.1 million.
Bitcoin, whose hashrate continues to rise to new highs, is also not out of danger due to the centralized nature of its mining. As previously reported, Binance CEO Changpeng Zhao raised the idea of undo the BTC blockchain after the $ 40 million Binance hack, but quickly moved away from it due to a huge reaction in the community.