Bitcoin is famous for having a decentralized network, which is a guarantee of a robust system and the unavailability of evidence. In operation for 11 years, the network has always had computational power to defend against attacks and has never been offline. But every now and then new theories arise about how to bring down the network.
According to an academic article published by researchers at Cornell Tech and the Technion Israel Institute of Technology, the Bitcoin network can be brought down with the help of 21% of miners. The research suggests that the strategy to “lock the blockchain” until then was unknown.
The researchers call the blockchain denial of service attack (BDoS). The study was presented at the ACM SIGSAC information security conference on October 20.
Pay miners to bring down the network
The researchers indicate that a BDoS is the first type of attack that "uses a reward mechanism to discourage participation in mining."
In a nutshell: the Bitcoin network consists of miners who use computing power to validate transactions and add them to the blockchain. Therefore, they receive a mining fee. In addition, there are also nodes that check that everything is right. They have no financial incentives.
The attack comes down to the attacker offering a mining reward to anyone who joins the attack.
In other words, the attack targets the reward system, discouraging miners from participating in the network. The attacker publishes a proof of work on the blockchain (with a mining reward advantage) causing other miners to have a mining disadvantage.
In theory, the reward would make other miners feel that they are in the minority and disadvantaged. According to the researchers, this means that “rational” miners will stop mining as soon as they discover they are losing money.
“If profitability is so great that all miners stop mining, the attacker can also stop mining. Then, blockchain comes to a complete standstill. "
Ittay Eyal, a professor at Technion and co-author of the study, defines the attack as “selfish mining”. The attacker needs to offer more than the miners earn with rewards. The aim of the attack is to destroy the currency, instead of profiting or stealing assets.
The cost of the attack, however, is salty, as to convince 21% of miners to join the attack would not come cheap. In addition, there are several ways to mitigate the attack.
The research authors suggest that Bitcoin will become more vulnerable to BDoS attacks as the industry grows and profitability declines.
As the Bitcoin network is made up of thousands of devices, nodes, and miners, a DoS attack is very difficult. The network is decentralized and therefore protected against these attacks.
Before the new survey, it was always thought that an attacker should obtain at least 51% of the computing power to bring down the network. This would not be necessary for a BDoS attack.
Theoretically, it is possible to lock the network with fewer resources.
They claim, therefore, that only 21% of the total computing power is needed to succeed in the attack.
The attack is theoretical and has never been attempted before.
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