Key Highlights
- Security expert “0xflorent” successfully retrieved approximately 1,003 ETH (valued at roughly $2 million) trapped in HongCoin’s 2016 ICO smart contract for almost nine years
- A coding error in the refund mechanism prevented participants from withdrawing their ETH after the token sale missed its fundraising target
- The researcher collaborated with HongCoin’s development team to leverage an integer overflow flaw in an administrative function to release the trapped assets
- 48 initial participants are now eligible to retrieve their ETH; two investors have already successfully withdrawn 96.5 ETH (approximately $193,000)
- The white hat hacker worked without any upfront compensation — accepting only voluntary tips from grateful investors
A cybersecurity professional has successfully recovered approximately 1,003 Ether valued at around $2 million that remained inaccessible in a 2016 initial coin offering smart contract for close to ten years.
These assets originally belonged to participants in the HongCoin token sale, an Ethereum-based project marketed as a community-governed investment vehicle. The fundraising campaign operated between August 29 and October 28, 2016, ultimately falling short of its capital target.
Following the unsuccessful campaign, the underlying smart contract should have initiated automatic refunds to all contributors. However, a critical flaw in the refund logic silently prevented this process from executing properly.
The cybersecurity expert, identified by the handle “0xflorent” or simply Florent, detailed the technical malfunction in a detailed thread on X. The refund mechanism contained logic that rejected any token holder whose balance exceeded a global tracking variable. Through years of scattered partial refunds, this counter had decreased to 356, effectively limiting total withdrawals to merely 3.56 ETH — substantially less than what most contributors were entitled to receive.
The smart contract was developed using an outdated version of Solidity, the primary programming language for Ethereum smart contracts. It included no safeguards against integer overflow vulnerabilities — a dangerous condition where numeric values increase beyond their maximum capacity and unexpectedly reset to zero or one. This particular weakness was subsequently addressed industry-wide through the implementation of SafeMath libraries.
The Technical Solution
Florent discovered a workaround by utilizing an administrative function built into the contract by the HongCoin development team. By invoking this function with precisely calculated input parameters, he could reset individual token holder balances to one, satisfying the refund verification requirements and triggering ETH releases.
This recovery operation required full cooperation. The administrative function was protected by the HongCoin team’s multisignature wallet, requiring team authorization for each individual transaction. Florent initiated contact via email, conducted thorough testing on a network replica, and the team subsequently approved 41 separate transactions — one for each affected participant. The entire operation spanned approximately one week.
Among the 48 qualifying participants, 41 required balance adjustments. The remaining seven held sufficiently small positions to receive immediate direct refunds.
Two participants have already successfully claimed a total of 96.5 ETH, currently worth approximately $193,000. Both individuals voluntarily compensated Florent with whitehat bounties, though no payment obligation existed. “There were no fees, no cut, no commission,” Florent confirmed to The Block.
A Track Record of Fund Recovery
This represents just one of Florent’s several recovery operations. On May 24, he documented the liberation of 19.33 Ethereum from two different legacy contracts — one from a defunct 2018 token sale and another from a Liquality Wallet user whose assets became locked in outdated atomic swap mechanisms.
Florent revealed that he recently deployed his own Ethereum node infrastructure and developed custom scanning software to identify contracts holding over 100 ETH. He systematically evaluates these candidates, searching for exploitable security weaknesses.
He also leveraged Claude Code to assist with contract categorization and pattern recognition, though he acknowledged the artificial intelligence tool has significant limitations when directly analyzing smart contract security vulnerabilities.
Florent expressed his desire to inspire more security professionals to focus on asset protection rather than theft. “It’s more rewarding morally, and it can also pay well,” he explained.
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