How are you? By Allah's grace, I'm doing very well.

Source

Although blockchain technology is generally considered to be very secure and hack-proof, it has a serious technical vulnerability, known as a '51% attack'. Simply put, it is a situation where an individual, hacker group, or organization controls more than half (at least 51 percent) of the total mining power or computing power of a particular blockchain network. The foundation of blockchain is decentralization, where decisions are made based on majority opinion. But when 51 percent of the power goes to a single party, that decentralization system breaks down and hackers gain complete control over the network.

How it works and its harmful effects

When a new transaction or block is added to a blockchain network, all the computers or nodes in the network verify it. If hackers somehow manage to own 51 percent of the computing power, they can change the general rules of the network to suit their own needs. By abusing this power, hackers are able to commit two major types of fraud. This is the most dangerous aspect of the 51% attack. Through this, hackers can spend the same cryptocurrency or coin once, change the blockchain ledger, bring that coin back to their wallet and spend it a second time. They create a secret blockchain chain and since they have 51% or more of the power, the fake chain they create is eventually recognized as the real chain on the network. If hackers want, they can prevent any new legitimate transactions from being added to the blockchain. As a result, transactions by ordinary users are blocked and the entire network becomes immobile. In addition, they do not allow any other honest miners to mine new blocks, as a result of which the mining rewards of the entire network are deposited only in the hackers' pockets. However, through this attack, hackers cannot completely delete old or past history transactions or steal coins directly from someone else's wallet even if they want to.

Which network is more vulnerable?

A 51% attack on a large blockchain network like Bitcoin or Ethereum is almost impossible. This is because the computing power or hash rate of these networks is so huge that controlling 51% of it requires billions of dollars of hardware and a huge amount of electricity, which is unrealistic for a single hacker or group to acquire. However, newer, smaller, or less popular cryptocurrencies on the market—those with much less total computing power in their networks—are prime targets for this attack. In crypto history, some smaller chains, such as Bitcoin Gold or Ethereum Classic, have had successful attacks in the past.

Conclusion

In short, a 51% attack is a weakness in the democracy of blockchain technology, where fraud can be legitimized by majority vote. This attack shakes the very foundation of cryptocurrency’s credibility and security. To avoid this risk, modern blockchain projects are now using Proof of Stake (PoS) or more advanced security mechanisms instead of Proof of Work, so that no one can monopolize power, even if they own a lot of money. Today's discussion concludes here. I hope you've found it interesting. Please share your thoughts on today's topic. Prayers for everyone. May everyone be well. Amen.