The Ministry of Science, Technology, and Communications of South Korea and the Korea Internet Promotion Agency are investigating the theft of the Coinrail and Bithumb exchanges. The hackers use an initially malicious code as an e-mail. The Ministry of Science, Technology, and Communications has confirmed that all employees of the Coinrail and Bithumb traders received a large number of e-mails before they were stolen. They attacked the exchange’s hot wallets through malicious code. Part of the exchange’s cryptocurrency (10 to 20%) is stored in a hot wallet, and most of the cryptocurrency (80 to 90%) is stored in a cold wallet that is disconnected from the Internet. When the Ministry of Science, Technology, and Information and Communication investigated the security situation of 21 exchanges at the beginning of the year, they found out that the security management of the cryptocurrencies and keys of the 18 exchanges was inadequate, and the 17 exchanges did not have an abnormal state monitoring system.