Binance has frozen funds linked to the $49 million breach of the Upbit crypto exchange after hackers tried to liquidate some of their ill-gotten gains.

Most of the action around the news took place on Twitter. At just after 16:00 UTC Wednesday, bot Twitter account Whale Alert warned Binance – which has previously committed to freezing any funds stemming from the hack – that roughly 137 ether (worth around $27,000 at press time) had moved from an address linked to the Upbit hacker group to its wallets.

Binance CEO Changpeng “CZ” Zhao tweeted soon after that the funds had been successfully frozen and the money would shortly be returned to Upbit. The time between hackers transferring the ether to Binance and the exchange blocking the funds was little more than half an hour.

Gone are the days when hackers could simply walk off into the sunset with their loot, as did the person who stole 850,000 bitcoin from Mt. Gox in 2014. Wallet addresses linked to suspected hackers are now tagged, and exchanges usually freeze any funds stemming from these wallets if they arrive on their servers.

In January 2019, Binance also froze funds linked to the $16 million Cryptopia hack.

See also: New Crypto Exchange Altsbit Says It Will Close Following Hack

Of course, it is still possible to launder funds. Something like 3,650 ether (worth roughly $725,000) has left the wallet linked to the Upbit hack in the past 24 hours, much of it passing rapidly through other wallets, likely to try and obfuscate the digital paper trail.

A report from security firm Uppsala earlier this year highlighted the Upbit hackers may have already laundered as much as $3.2 million worth of ether through exchanges, including Binance and Bitfinex, by only pushing tiny amounts through each time to avoid any red flags.

See also: Hacker Exploits Flaw in Decentralized Bitcoin Exchange Bisq to Steal $250K

It’s not clear what the hackers’ motivation was for sending $27,000 worth of ether to Binance on Wednesday. In the grand scheme of things, it’s not a large amount considering they managed to steal $49 million in total last November. One can speculate they might have been testing the exchange’s response times to see if larger amounts might slip through unnoticed.