Attackers Exploit OpenSea Loophole to Snatch and Resell Rare NFTs

A bug in the OpenSea NFT marketplace has enabled hackers to snatch up rare NFTs from owners for far below market value and resell them for hefty profits. 

At least three attackers exploited a bug on the marketplace, making away with over $1 million as of Monday, according to blockchain analytics firm Elliptic. One of the alleged opportunists bought a Mutant Ape Yacht Club NFT for $10,600 worth of ether, selling it hours later for $34,800 worth of ether.

“The exploit appears to originate from the ability to re-list an NFT at a new price, without canceling the previous listing,” Elliptic said in a report. “Those previous listings are now being used to purchase NFTs at prices specified at some point in the past — which is often well below current market prices.”

One attacker, who goes by “jpegdegenlove” online, paid roughly $133,000 for seven NFTs before quickly flipping them on the platform for $934,000 worth of ether. 

Suspicious activity picked up over the past day but the bug has been present for weeks and was flagged in a Jan. 1 tweet. The marketplace was exploited over eight times in a roughly eight-hour-span on Monday morning. A wallet address associated with multiple purchases has made a total profit of $878,288 worth of ether from the exploit, according to blockchain analytics provider Nansen. 

“The fact that a user could buy at previous prices and flip NFTs without any form of verification points to the centralization issue in NFTs as they stand right now,” Jenna Pilgrim, CEO of blockchain media licensing startup Streambed, told Blockworks.

“OpenSea does a great job at creating a solid user interface, but unfortunately does so at the cost of security,” she added. 

In a turn of events, “jpegdegenlove” later compensated two of their victims, transferring them a combined total of $75,000 worth of ether, according to Elliptic. 

Charles Guillemet, CTO of hardware wallet developer Ledger, said that it is currently not safe for NFT holders to have their assets listed on OpenSea. “It’s very difficult to use this platform securely right now,” he said on a Twitter space Monday. “The only thing we can do is to mitigate the risk.”

OpenSea has yet to publicly address the exploit and did not immediately respond to Blockworks’ request for comment on the matter.

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