The hacker behind the $7.5 million KiloEx exploit returned $5.5 million worth of cryptocurrency four days after the attack.

Decentralized exchange (DEX) KiloEx suspended platform operations after suffering a $7.5 million exploit, Cointelegraph reported on April 15.

In a surprising turn of events, the wallet address behind the exploit has returned $5.5 million worth of cryptocurrency to the DEX. 

“#KiloEx exploiter -labeled addresses have returned ~$5.5M worth of cryptos to #KiloEx,” according to an April 18 X post from blockchain security platform PeckShieldAlert.

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The unexpected repayment occurred after KiloEx offered the hacker a $750,000 “white hat” bounty — 10% of the stolen amount — if they returned 90% of the looted assets.

The platform said it was working with law enforcement and cybersecurity firms, including Seal-911, SlowMist and Sherlock, to uncover more about the hacker’s activity and identity.

The initial attack may have been caused due to a “price oracle issue,” where the information used by a smart contract to determine the price of an asset is manipulated or inaccurate, leading to the exploit, PeckShield said in an April 14 X post.

Related: Top 100 DeFi Hacks: Offchain attack vectors account for 57% of losses

This is a developing story, and further information will be added as it becomes available.