Netsky-P worm has accounted for almost a quarter of all virus incidents reported in 2004, making it the year’s hardest hitting virus of 2004. The German teenager responsible for more than 50% of all the virus incidents was Sven Jaschan. Sasser, the year’s third most prevalent worm, does not use email to propagate. Sasser spread via the internet, attacking vulnerable Windows computers, which were not updated with a critical Microsoft security patch. This patch was made available only 2 weeks before Sasser was first seen. The time period between patch availability and worm exploit is getting shorter than ever.