New version of Sasser undermines lone coder theory

Worm turns up after arrest of prime suspect

By John Leyden, 10th May 2004

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The appearance of a new version of the infamous Sasser worm shortly after the arrest of its admitted author has fuelled speculation that its creator worked with other virus writers.

Sasser-E was first spotted three hours and 45 minutes after the arrest of Sven Jaschan, 18, from Rotenburg in northern Germany at 2pm on Friday afternoon (local time). Either earlier sightings of the fast-spreading worm were missed or Sasser-E was released by someone other than Jaschan, who was released from police custody after the new version of the worm arrived onto the scene.

Spanish AV firm Panda Software said the appearance of the variant showed there was an "organised group of delinquents" involved in distributing copies of the prolific worm.

Finnish AV firm F-Secure is not so sure: "We believe Mr. "SJ" (who has confessed to writing all the Sasser and NetSky variants) had distributed this version shortly before his arrest. He has been released on bail, but this was only after first reports of this new variant were in. The E variant does not appear to be a hack done by someone else." Circumstantial evidence led F-Secure and many in the AV community to suspect that the NetSky series was the work of multiple authors, a conclusion undermined by Jaschan's confession.

Sasser-E uses the same Windows vulnerability as previous versions to spread across vulnerable Windows 2000 and XP machines, causing them to become unstable and shutdown. Unlike previous version, Sasser-E gives a warning from the "SkyNet Team" about the vulnerability it exploits. Unlike the first four Sassers but like many NetSky variants, Sasser-E tries to remove the Bagle worm. Advice of protecting computers against Sasser can be found here. ®