The DAO hack drained 3.6M ETH 10 years ago, triggering Ethereum hard fork

A reentrancy exploit took funds now worth $6.26 billion after a flagged vulnerability remained unpatched pending community approval, leading to the split that created Ethereum Classic.

ETH

Summary

A decade ago, an attacker exploited The DAO using a reentrancy exploit (smart contract vulnerability that repeatedly withdraws funds), draining 3.6 million ETH, an amount the source says is now worth $6.26 billion. The flaw had been identified weeks earlier, but fixes were still awaiting community approval when the attack happened. The incident became one of crypto’s defining governance crises, ultimately prompting a hard fork (blockchain split creating a new chain) that created Ethereum Classic.

Terms & Concepts
  • reentrancy exploit: A smart contract flaw allowing repeated withdrawals before balances update.
  • hard fork: A blockchain split that creates a separate version of the network.
  • Ethereum Classic: The chain that continued after Ethereum split following The DAO hack.