A security researcher operating under the alias 0xflorent has successfully unlocked approximately $2 million in ether (ETH) that had remained inaccessible for nine years, after discovering and exploiting an integer-overflow vulnerability in a legacy smart contract from HongCoin's 2016 initial coin offering.

Market Context

The recovery comes amid heightened scrutiny of DeFi security practices, with April 2026 alone seeing hundreds of millions of dollars drained across protocols. The landmark hack of Kelp DAO, which resulted in roughly $293 million in losses, has cast a spotlight on the fragility of legacy smart contract code written during crypto's early days.

Analysis

0xflorent identified that HongCoin's token sale contract contained an unpatched integer-overflow flaw in its refund function. The bug caused the contract to reject any investor whose token balance exceeded a global counter that had been dragged down to 356 over years of partial refunds, effectively capping individual refunds at 3.56 ETH regardless of actual holdings.

An admin function on the contract lacked the overflow protections later incorporated into Solidity's programming language. By calling this function with specific input values, 0xflorent reset affected holders' balances, allowing refund checks to pass and releasing the trapped funds. The recovery required coordination with HongCoin's multisig wallet administrators, as the admin function necessitated multi-signature authorization.

Unlike malicious exploits, this whitehat operation involved full collaboration with the project team. After validating the unlock sequence on a test fork of Ethereum's mainnet, 0xflorent emailed the HongCoin team, who signed 41 transactions—one per blocked holder—freeing approximately 1,003.62 ETH. An additional seven holders held small enough balances to refund directly without the workaround.

Key Numbers

- 1,003.62 ETH unlocked (approximately $2 million at current prices)

- 48 original HongCoin investors eligible to claim refunds

- 43 transactions executed by project team multisig to process claims

- Two investors have already claimed a combined 96.5 ETH ($193,000)

What to Watch

This recovery marks 0xflorent's second publicized whitehat success in eight days. On May 24, the researcher returned approximately $40,590 in crypto—including 19.329 ETH from a failed January 2018 ICO and funds from expired atomic swaps—to their original owners. Traders should monitor whether other legacy contracts with similar vulnerabilities emerge for coordinated recovery efforts, as institutional interest in on-chain security forensics continues to grow.