The most ridiculous crypto heist? A hacker minted $10億 DOT worth, but only stole $23萬.

Hackers exploited a vulnerability in the Hyperbridge cross-chain bridge to mint 1 billion DOT tokens out of thin air, with a face value of $1.19 billion. However, due to severe market liquidity shortages, they only cashed out about $237k.

Cryptocurrency attack incidents are numerous, but cases like this—“taking big risks for small gains”—are quite rare. Earlier today (13th), hackers exploited a flaw in the Hyperbridge cross-chain bridge to mint 1 billion Polkadot (DOT) tokens on Ethereum, with a nominal value of $1.19 billion. Yet when they tried to sell these tokens, they only managed to get about $237k worth of ETH due to liquidity issues.

It should be clarified that the attack targeted the “cross-chain bridge smart contract,” so the native DOT tokens on the Polkadot mainnet were not affected. The main cause of this vulnerability was that Hyperbridge’s EthereumHost contract failed to properly verify the authenticity of messages before passing cross-chain information to the TokenGateway.

Image source: X/@OnchainLens

Cross-chain bridges have always been the most vulnerable part of blockchain architecture because they hold management permissions over token contracts. Once the verification mechanism is compromised, hackers can easily gain the power to mint unlimited tokens.

Attack methods: forging messages, taking over management rights, unlimited minting

On-chain tracking shows that the hacker submitted a forged message via dispatchIncoming, successfully directing it to TokenGateway.onAccept. The system was supposed to verify the authenticity of this message based on the status on the Polkadot chain, but the verification mechanism recorded the promise value as “all zeros,” meaning the verification process was completely bypassed or nonexistent. As a result, the system mistakenly treated this fake message as a legitimate command.

The accepted message immediately executed the changeAdmin function on the bridge’s Polkadot token contract, transferring admin rights to the attacker’s address. After gaining management control, the attacker minted 1 billion DOT tokens in a single transaction, then used Odos Router V3 to deposit these tokens into the DOT-ETH trading pool on Uniswap V4. After multiple swaps at slightly different prices, they ultimately withdrew about 108.2 ETH.

“Liquidity shortage” becomes a protective shield

In financial markets, “liquidity shortage” is usually a headache for large whales, but ironically, in this case, the liquidity shortage became an invisible shield, greatly limiting the hacker’s profit potential.

Because the liquidity depth of DOT on Ethereum is extremely limited, it cannot absorb the 1 billion tokens minted out of thin air. When the hacker rushed to sell and cash out, severe slippage caused the actual price per token to drop to less than one cent.

In a bridge with deeper liquidity or higher value assets, the same vulnerability could cause losses dozens of times greater. As of writing, DOT’s trading price is about $1.17, down 5% in the past 24 hours.

This incident again demonstrates that even if hackers have “unlimited minting rights,” whether they can successfully arbitrage ultimately depends on market liquidity and trading depth. The well-known blockchain security firm CertiK later confirmed the attack and stated that the hacker profited about $237k by minting and selling the bridge tokens.

As of now, Hyperbridge has not issued any public statement regarding the hacker incident.

Image source: X/@CertiKAlert

• This article is reprinted with permission from: “BlockCast”
• Original title: “The Most Ridiculous Heist? Hacker Mints $1 Billion in $DOT, Only Steals $237K Due to ‘This Reason’”
• Original author: Block Sister MEL