When we speak of viruses, the topic of worms is not far behind. They are another major menace. Unlike viruses, which by definition require some sort of action to occur in order to trigger their mischief, worms are entirely self replicating. Worms effectively use the power of networks, malware, and speed to spread very dangerous and effective pieces of malware
One example is the SQL Slammer worm from the early 2000s. At the time, the Slammer worm was responsible for widespread slowdowns and severe denials of services on the Internet. The worm took advantage of the fact that systems that had SQL Server or SQL Server’s Desktop products were vulnerable to a buffer overflow. Although Microsoft had released a patch six months prior to the worm’s debut, many organizations had neglected to install the patch. With this vulnerability still present on so many systems, the conditions for the attack were ripe. On the morning of January 25, 2003, the worm went active—and within 10 minutes 75,000 machines were infected, along with many more over the next few hours.