Date:: April 22nd, 2017
Amount Stolen:: $4,800,000 (3831 BTC) + "17% of assets"
Date:: December 19th, 2017
Amount Stolen:: $2,650,000
Two hacks and three name changes in one year.
Before becoming Youbit, Yapizon was hacked for the first time, losing 3,831 BTC in the process. Yapizon shared that it would dock remaining customer balances by the same amount to spread the burden of the losses.
Following a hack that cost 17% of the exchange’s holdings, Youbit announced it was closing down. Youbit later declared bankruptcy as a result of hack.
Youbit (formerly Yapizon) suffered multiple attacks involving a - $4.8 million loss in April 2017 and then 17% of its overall assets in December 2017, forcing the exchange to close.
This was the second time that Youbit had suffered a hack this year. In April, the exchange suffered a theft of nearly 4,000 bitcoins in a cyber attack that South Korean authorities allege was perpetrated by North Korea, according to a Reuters report.
Youbit said that it beefed up its security policies following the April hack and that the other 83 percent of the exchange’s funds were stored safely in a cold wallet. Nevertheless, Yaipan, the company that operates the exchange, filed for bankruptcy on Tuesday and halted trading on the platform.
According to the announcement, the exchange has marked down customer assets to 75 percent of their market value, and customers can withdraw them immediately. The company said it will repay the remainder of the funds at the conclusion of the bankruptcy proceedings, by which time it will have filed an insurance claim and sold the company’s operating rights.
As far as I can tell, only the "17% of assets" aka the December 2017 hack is attributed to DPRK.
Exchange 2 in US v 113
In the 2023 UN Report, they attributed both the April and December hacks to DPRK, as expected.