25% Attack (variant of majority attack)

A 25% Attack, also known as a variant of majority attack, occurs when a single entity or group of entities controls 25% or more of the mining power in a cryptocurrency network. This gives them the ability to manipulate the blockchain by being able to overtake the consensus of the network.

With this amount of control, the attacker can potentially double spend their coins, reverse transactions, or exclude certain transactions from being confirmed. This can lead to chaos and instability in the network, undermining the trust and security of the cryptocurrency.

To execute a 25% attack, the attacker needs a significant amount of computational power to outpace the rest of the miners in the network. This type of attack is concerning because it undermines the decentralized nature of cryptocurrencies and compromises the integrity of the blockchain. As a result, many cryptocurrencies have implemented protocols and mechanisms to prevent such attacks and maintain the security of the network.