The culprit in the attack was a ransomware virus called WannaCrypt.
Ransomware itself is not a new concept. Ransomware first appeared in 1989 as a piece of malware called "AIDS Trojan," written by Joseph Popp. In 1996, security experts at Columbia University and IBM wrote a document called Cryptovirology that clearly outlined the concept of ransomware: the use of malicious code to interfere with the normal use of a poisoned person, and the only way to get back to normal was to pay money.
Initially, ransomware was the same as what we see now, in the form of encrypting files and charging to decrypt them, only the encryption methods used were different. Later, in addition to encryption, also appeared through other means of ransom, such as forced display of pornographic images, the threat of spreading the browsing record, the use of false information blackmail and other forms of ransomware to the victim to ask for the amount of money, this type of ransomware virus has been constantly appearing in recent years.