The ZKsync Association has confirmed the recovery of $5 million worth of stolen tokens from an April 15 ZKsync security incident involving its airdrop distribution contract.

The hacker agreed to accept a 10% bounty and return 90% of the remaining stolen tokens, transferring the ZKsync Security Council almost $5.7 million across three transfers on April 23.

“We’re pleased to share that the hacker has cooperated and returned the funds within the safe harbor deadline,” ZKsync Association posted to X on April 23, which was later reposted by ZKsync’s X account.

Matter Labs, the company behind the ZKsync protocol, also reposted the news shared on X.

The ZKsync X account previously confirmed that no user funds were compromised.

_Source:__ZKsync Association_

The hacker sent two transfers on the ZKsync Era blockchain, consisting of $2.47 million worth of ZKsync (ZK) tokens and $1.83 million worth of Ether (ETH) to the ZKsync Security Council’s ZKsync Era address.

Another 776 ETH worth nearly $1.4 million was also sent to their security council’s Ethereum address, Etherscan data shows.

The first transfer was made on April 23 at 2:39:57 pm UTC on and the last transfer was made roughly 13 minutes later — all within the 72-hour window that ZK Sync had initially set.

ZKsync Association said the company would publish a final report revealing more details from the security incident.

## How the hack happened

The hacker breached ZKsync’s admin account, allowing them to exploit the airdrop distribution contract’s sweepUnclaimed() function to mint 111 million unclaimed ZK tokens, worth approximately $5 million at the time of the April 15 attack.

The hack occurred while ZKsync was in the process of airdropping 17.5% of ZK’s token supply to ecosystem participants.

The recovered amount — almost $5.7 million — exceeded the $5 million originally stolen due to a rise in the market value of the stolen tokens, with ZK and ETH increasing 16.6% and 8.8% respectively since the April 15 attack, according to CoinGecko data.

Despite the asset recovery, the ZK token failed to rise substantially on the news and is currently down 0.2% over the last 24 hours.

ZKsync Era is an Ethereum layer 2 solution that uses zero-knowledge rollups to batch and process transactions offchain. It has nearly $59 million in total value locked on its chain and has over $2 billion in real-world assets onchain, according to DefiLlama and RWA.xyz.

_**Magazine:**__**Ethereum maxis should become ‘assholes’ to win TradFi tokenization race**_