At number 10: Morris (1988), Robert Morris claims that he wrote the worm in an effort to gauge the size of the Internet (duh!), unfortunately it had a bug that infected computer multiply times and thus came the “Denial-of-Service” attack.
9: Storm (2007), at the center of a denial-of-service attack was http://www.microsoft.com, where during Symantec’s test on an infected machine, it sends out almost 1,800 e-mails in a five-minute period.
8: Sasser (2004), this worm exploited vulnerable network ports, meaning that it could spread without user intervention.
7: Blaster (2003), just like storm, this caused a denial-of-service to windowsupdate.com, which included the message, “billy gates why do you make this possible? Stop making money and fix your software!!”
6: Code Red (2001), Web sites defaced by the phrase “Hacked By Chinese!”
5: Nimda (2001), within 22 minutes, Nimda became the Internet’s most widespread worm (yeah that fast!).
4: Slammer (2003), a worm that was mistaken by some countries to be an organized attack against them.
3: Melissa (1999), i thought this story was quite amazing… see Melissa was an exotic dancer, and David Smith was obsessed with her (and also with writing viruses). this virus was so know it rocked the internet world between 1999 and 2005.
2: Conficker (2009), the newest kid on the block yet promising to be the worst. the Conficker worm has created a secure, worldwide infrastructure for cybercrime. the worm allowed installation of softwares to infected machines and many have yet to figure out what it would do!
last and the least, perhaps the most dear to us IT PINOYs, is the I Love You virus. who wouldn’t open an email from someone telling they love you. well, many got fooled! by May 2000, 50M infections had been reported, which included The Pentagon, the CIA, and the British Parliament. certainly nothing for us IT PINOYs to be proud about but, hey it landed us on the IT map!
read more [abcnews.go.com]