An infamous computer worm

Sasser started spreading on April 30, 2004.

The worm did not cause irreparable harm to computers or data, but it slowed computers and caused some to continually crash and reboot without explanation.

The Sasser worm is different than other viruses in that users do not have to open a file attachment to be affected by it. Instead, the worm seeks out Windows computers with a security flaw and then sabotages them.  

The effects of Sasser included the news agency Agence France-Presse (AFP) having all its satellite communications blocked for hours and the US flight company Delta Air Lines having to cancel several trans-Atlantic flights because its computer systems had been swamped by the worm. The Nordic insurance company If and their Finnish owners Sampo Bank came to a complete halt and had to close their 130 offices in Finland.

On May 7, 2004 an 18-year-old German computer science student - Sven Jaschan from Rotenburg - was arrested for writing this worm at the age of 17. He escaped the maximum sentence of five years in prison though, since he was being tried as a juvenile. He was given a 21-month suspended sentence.