ZKsync recovers $5 million after hacker returns stolen tokens

ZKsync (CRYPTO:ZK) has recovered approximately $5.7 million in stolen tokens following a security breach on April 15 that targeted its airdrop distribution contract.

The attacker exploited a vulnerability in the contract’s `sweepUnclaimed()` function to mint 111 million unclaimed ZK tokens, which were worth around $5 million at the time.

Following the breach, the hacker agreed to a bounty arrangement, returning 90% of the stolen assets while retaining 10% as a reward.

The ZKsync Security Council confirmed receiving three transfers on April 23 totaling nearly $5.7 million.

These transfers included approximately $2.47 million in ZK tokens and $3.23 million in Ether (CRYPTO:ETH).

All funds were returned within the 72-hour deadline set by ZKsync, with the first transfer recorded at 2:39 pm UTC and the final one occurring 13 minutes later.

“We’re pleased to share that the hacker has cooperated and returned the funds within the safe harbor deadline,” stated the ZKsync Association in a post on X.

Matter Labs, the team behind ZKsync, also acknowledged the update via social media.

On-chain data from Etherscan confirmed that 776 ETH, valued at nearly $1.4 million, was sent to the Security Council’s Ethereum address.

ZKsync emphasised that no user funds were affected during the incident.

The total amount recovered exceeded the original value of the stolen assets due to price increases in ZK and ETH following the breach.

According to CoinGecko, ZK rose 16.6% and ETH increased by 8.8% since the exploit occurred.

Despite the recovery, the price of ZK declined slightly by 0.2% in the past 24 hours.

ZKsync Era, an Ethereum layer 2 network using zero-knowledge rollups, currently holds nearly $59 million in total value locked and over $2 billion in onchain real-world assets, based on data from DefiLlama and RWA.xyz.

The ZKsync Association plans to publish a final report detailing the security incident.

At the time of reporting, the ZKsync (ZK) price was $0.05566.