May brought a sharp change of direction, with the appearance of a large number of malicious programs which propagated by exploiting technical, rather than human, vulnerabilities. In the course of the month, one completely new vulnerability was detected, which was rapidly exploited by virus writers. Virus writers reacted quickly Worm.Win32.Sasser was the first program to exploit the newly publicized vulnerability, and made its debut on 30th April. The war of the worms cooled as virus writers started to focus on the new opportunities provided by the new vulnerability.”]
Source: https://securelist.com/malware-evolution-may-roundup/100376/