The string of recent cryptocurrency thefts isn't stopping any time soon. South Korean crypto exchange Upbit has confirmed that 342,000 Etherium coins, worth about $49 million, were transferred from its wallet to an "anonymous wallet" (read: a thief) on November 27th. The exchange quickly suspended all crypto deposits and withdrawals and moved all assets to offline wallets that couldn't be attacked. Upbit said it would "immediately" replace the missing Ethereum with its own assets, but that it would take two weeks before deposits and withdrawals would resume -- if you were depending on that virtual money, you might be in trouble.
The exchange encouraged community members to block deposits from the offending wallet, but didn't have leads to identify the owner. There's a wide range of potential candidates. It could be typical online criminal organizations, an inside job, or nation states hoping to pad their funds when sanctions leave them cash-strapped.
This isn't the largest crypto theft to date. Coincheck lost $400 million in NEM tokens to a hack at the start of 2018, for instance. However, it's still doing significant damage. It also suggests that exchanges may need to do more to lock down transfers to prevent large-scale theft like this.