A successful attack on the Ethereum Classic blockchain would cost as little as $1.5 million. $55 million would be enough to “bankrupt” the whole network, leaving an intruder with $1 billion in profit.
The cost of a 51% attack on the Bitcoin Cash network would be 250 BTC per day. The same attack on Bitcoin Gold would cost only 26 BTC. The attack may persist up until the developers release a fix or the price declines to the level at which carrying out the attack is no longer efficient.
These are the findings of Husam Abboud, a researcher at the Brazilian university FECAP. He developed an alternative model for calculating the cost of a 51% attack called Rindex v2.0. Mr. Abboud doesn’t pay attention to the expenses related to the acquisition of mining equipment and electricity consumption since an attacker can instead simply rent hashing power. For example, if an ETH miner with 2.5% of Nethash switches to mine ETC, they will then have 51% of ETC Nethash. The one-day cost of a 51% attack on ETC would equal ETH mining profit per day, or 525 ETH.