Another Bitcoin hard fork, Bitcoin Gold (BTG), recently underwent a 51% attack, which costs about 7,167 BTG ($72,000). This information was revealed by the president of MIT Bitcoin Club, James Lovejoy, who detected two deep reorgs on BTG blockchain, both of which were double-spends.

Bitcoin Gold ($BTG) was 51% attackedhttps://t.co/KxFvrsOhuO — James Lovejoy (@metalicjames) January 24, 2020

He noted that, in both instances, the attacker blocks were mined with the addressGWrW5dTZf5XwGWoJuqRKdzkzZFkwtWSqaP in the Coinbase transaction. He added that, the Binance deposits of BTG at the time of the attack, were credited to one’s account for trading after 6 confirmations, and were available for withdrawals after 12 confirmations.

Thus, a 14 or 15 block reorg would evade both Binance’s escrow periods, says Lovejoy. Since then, Lovejoy claims Binance has increased its withdrawal requirement for BTG to twenty confirmations.

Lovejoy claimed that there is a possibility that these attacks were profitable if the double-spends succeeded to defraud the attackers counterparty. It could also be a break-even if the double-spends doesn’t go through successfully.

According to Lovejoy, this is an indication that a confirmation requirement on the order of tens of blocks for BTG is still insufficient to make the budget constraint to launch an attack significant.

The attackers managed to withdraw 1,900 BTG and 5,176 BTG through two separate transactions on January 23 and 24 respectively.

This is not the first time BTG has suffered a 51 attack like this. In May 2018, it sustained the attack by a malicious actor in which 388,000 BTG was stolen from several exchanges.