Kaspersky Labs quarterly report covers the main trends of the fourth quarter of 2005, including viruses for new platforms, and viruses for zero day vulnerabilities. The final report for 2005 covers viruses for the first quarter, including Sober, Slammer, Sasser, Mytob and Lovesan. Sober.y was one of the most successful viruses of 2005 in terms of the number of infected machines and infected messages in mail traffic. The worm used all the victim machines for mass mailing purposes, and tens of millions of copies of the worm started circulating.”]
Source: https://securelist.com/malware-evolution-october-december-2005/36069/