The FT digs into the $500m theft of XEM coins in Japan by an anonymous hacker. Following a crumb trail on the XEM blockchain they detail the timeline of the heist during the dead of night on Jan 26th.
In the early hours of January 26 a different kind of user found Coincheck all too friendly. Like a cat burglar in the dead of night, a hacker penetrated the company’s security and found a fortune in XEM sitting in a “hot wallet”, a computer connected to the internet. Best practice is to keep cryptocurrency in a “cold wallet”, isolated from the network. There is still no information on the location of the hacker, their identity or how the theft was carried out.
https://www.ft.com/content/7010982c-0800-11e8-9650-9c0ad2d7c5b5