White hat hackers help recover 2 million dollars' worth of ETH locked in the 2016 ICO contract

According to The Block, a developer using the pseudonym Florent helped rescue approximately 1003 ETH (worth about $2 million) that had been trapped in the 2016 HongCoin ICO contract for nine years through white hat hacking techniques. The ICO was supposed to automatically refund due to not meeting the funding target, but a coding error caused the funds to be locked. The contract used an old version of the Solidity language, lacking overflow protection mechanisms.

Florent discovered that by calling the team's admin function and inputting a specific value, he could reset the holder's balance to 1, thereby releasing the ETH through a refund check. This admin function was restricted to HongCoin's multi-signature address. Florent contacted the team and, after verifying the process on the test network, the team signed the unlock transaction themselves. The entire process took about a week, during which the team signed 41 transactions covering approximately 1000 ETH. So far, two investors have claimed 96.5 ETH and voluntarily paid Florent a white hat reward. Florent stated that his motivation was curiosity and understanding how the old contract worked.