When a single group controls more than half of a blockchain’s mining power, they can launch a 51% attack, a type of consensus attack where an entity dominates the network to rewrite transaction history. Also known as a majority attack, this isn’t science fiction—it’s a real threat that’s happened before, and could happen again. The whole point of blockchain is to be trustless and decentralized. But if one miner or group holds more than half the computing power, they can outvote everyone else. That means they can stop new transactions, reverse payments they made (double spending), and block other miners from confirming blocks. It doesn’t mean they can steal coins or create new ones—but it does mean they can break the chain’s credibility.
This isn’t just about Bitcoin. Smaller blockchains with low hash rates are way more vulnerable. Networks like Ethereum Classic and Verge have been hit by 51% attacks in the past, costing millions in stolen funds. Why? Because they’re easier to rent. Attackers can hire cheap hash power from services like NiceHash and overwhelm these chains in hours. Big chains like Bitcoin or Ethereum? Nearly impossible. The cost to control 51% of Bitcoin’s network would run into billions—so it’s not worth it. But for smaller coins, it’s a cheap way to make a quick profit. That’s why you should always check a coin’s hash rate before investing. If it’s low and growing slowly, it’s a red flag.
What makes a 51% attack possible? It’s not a bug—it’s a trade-off. Blockchains rely on proof-of-work to secure themselves, but that same system lets miners compete for rewards. If one miner gets too big, the system breaks. That’s why some projects now use proof-of-stake instead. In proof-of-stake, you need to own a lot of the coin to attack it—and attacking your own investment makes no sense. But even then, nothing’s perfect. Attackers can still try to manipulate governance or exploit smart contracts. The real lesson? Security isn’t just about code. It’s about distribution. If mining or staking power is too concentrated, the chain is fragile.
What you’ll find in the posts below aren’t just theory or fear-mongering. These are real cases—like how Iran uses state-controlled mining to bypass sanctions, how Pakistan’s tax rules affect crypto behavior, and how scams like Apple Network (ANK) and TigerMoon (TIGERMOON) thrive in unsecured networks. You’ll also see how blockchain forensics helps track these attacks, how smart contract audits can prevent exploitation, and why exchanges in Turkey and the UK are now forced to follow strict licensing rules. All of it connects back to one thing: when control is too centralized, the system cracks. The 51% attack is the clearest example of that. And if you’re holding crypto, you need to know where the weak spots are.
A 51% attack lets an attacker double-spend cryptocurrency by controlling most of a blockchain’s mining power. While Bitcoin is safe, smaller coins like Ethereum Classic have been hacked. Learn how it works, who’s at risk, and how to stay protected.
