Mydoom is a computer worm affecting Microsoft Windows. It was first sighted on January 26, 2004. It became the fastest-spreading e-mail worm ever (as of January 2004), exceeding previous records set by the Sobig worm and ILOVEYOU, a record which as of 2019 has yet to be surpassed.
Mydoom appears to have been commissioned by e-mail spammers to send junk e-mail through infected computers. The worm contains the text message "andy; I'm just doing my job, nothing personal, sorry," leading many to believe that the worm's creator was paid. Early on, several security firms expressed their belief that the worm originated from a programmer in Russia. The actual author of the worm is unknown.
Speculative early coverage held that the sole purpose of the worm was to perpetrate a distributed denial-of-service attack against SCO Group. 25 percent of Mydoom. A-infected hosts targeted www.sco.com with a flood of traffic. Trade press conjecture, spurred on by SCO Group's own claims, held that this meant the worm was created by a Linux or open-source supporter in retaliation for SCO Group's controversial legal actions and public statements against Linux. This theory was rejected immediately by security researchers. Since then, it has been likewise rejected by law enforcement agents investigating the virus, who attribute it to organized online crime gangs.
Initial analysis of Mydoom suggested that it was a variant of the Mimail worm, hence the alternate name Mimail.R, prompting speculation that the same people were responsible for both worms. Later analyses were less conclusive as to the link between the two worms.
Mydoom was named by Craig Schmugar, an employee of computer security firm McAfee and one of the earliest discoverers of the worm. Schmugar chose the name after noticing the text "mydom" within a line of the program's code. He noted: "It was evident early on that this would be very big. I thought having 'doom' in the name would be appropriate."
MyDoom is the most devastating computer virus to date, which caused more than $38 billion in damage.