Sven Jaschan (born April 29 1986) is the self-confessed author of the NetSky and Sasser computer worms.

Jaschan lives in the village of Waffensen , Germany and attends a computer science school in nearby Rotenburg. The student admitted writing and releasing the two damaging worms when arrested by German police on 7 May 2004 after a three-month long international investigation. Following his arrest, Microsoft confirmed that they had received tip-offs from more than one source, and that the $250,000 reward for identifying the author of the NetSky worm would be shared between them. A Microsoft official attended the arrest and the initial interrogation. Some sources claim that at least one tip-off came from a classmate of Jaschan's to whom he had boasted of his activities. Several of Jaschan's classmates also came under investigation following Jaschan's arrest. There was also speculation that he had written the worms to drum up business for his mother and stepfather's PC support business. In an interview in July 2004, Jaschan claimed to have written the Netsky worms in order to remove infection with MyDoom and Bagle worms from victims' computers. He also confirmed that a friend and classmate had given a tip to Microsoft.

A report by Sophos in August 2004 claimed that Jashan's viruses were responsible for 70% of the infections seen in the first half of that year. Following his initial arrest, Jaschan was released pending trial. Several companies and institutions have posted damage claims against him. However, because Jaschan was under 18 when he released the viruses, it is possible he will not receive a harsh sentence.

He was employed by the German security company Securepoint on September 1 2004. In retaliation, the prestigious German H+BEDV antivirus company officially halted its cooperation with Securepoint on 15th November 2004. In general, IT security companies are skeptical about rehabilitating and rewarding VXers or crackers.