Blaster (also known as Lovsan, Lovesan, or MSBlast) was a computer worm that spread on computers running operating systems Windows XP and Windows 2000 during August 2003.
The worm was first noticed and started spreading on August 11, 2003. The rate that it spread increased until the number of infections peaked on August 13, 2003. Once a network (such as a company or university) was infected, it spread more quickly within the network because firewalls typically did not prevent internal machines from using a certain port. Filtering by ISPs and widespread publicity about the worm curbed the spread of Blaster.
In September 2003, Jeffrey Lee Parson, an 18-year-old from Hopkins, Minnesota, was indicted for creating the B variant of the Blaster worm; he admitted responsibility and was sentenced to an 18-month prison term in January 2005. The author of the original A variant remains unknown.