Just weeks after Korean crypto exchange Coinrail lost $40 million through an alleged hack, another in the crypto-mad country -- Bithumb -- has claimed hackers made off with over $30 million in cryptocurrency.
Coinrail may be one of Korea's smaller exchanges, but Bithumb is far larger. The exchange is one of the world's top ten ranked based on trading of Ethereum and Bitcoin Cash, and top for newly-launched EOS, according to data from Coinmarketcap.com.
In a now-deleted tweet, Bithumb said today that 35 billion won of tokens -- around $31 million -- were snatched. It didn't provide details of the attack, but it did say it will cover any losses for its users. The company has temporarily frozen deposits and trading while it is in the process of "changing our wallet system" following the incident.
Days prior to the hack, Bithumb said on Twitter that it was "transferring all of asset to the cold wallet to build up the security system and upgrade" its database. It isn't clear whether that move was triggered by the attack -- in which case it happened days ago -- or whether it might have been a factor that enabled it.
[Notice for the restart of service]
We are transferring all of asset to the cold wallet to build up the security system and upgrade DB. Starting from 15:00 pm(KST), we will restart our services and notice again as soon as possible. Appreciate for your support.
— Bithumb (@BithumbOfficial) June 16, 2018
A tweet sent days before Bithumb said it had been hacked
There's often uncertainty around alleged hacks, with some in the crypto community claiming an inside job for most incidents. In this case, reports from earlier this month that Bithumb was hit by a 30 billion won tax bill from the Korean government will certainly raise suspicions. Without an independent audit or third-party report into the incident, however, it is hard to know exactly what happened.
That said, one strong takeaway, once again, is that people who buy crypto should store their tokens in their own private wallet (ideally with a hardware key for access) not on an exchange where it could be pinched by an attacker. In this case, Bithumb is big enough to cover the losses, but it isn't always that way and securely holding tokens avoids potential for trouble.
- This article originally appeared on TechCrunch.