A GERMAN teenager is facing a jail term after admitting yesterday to creating and unleashing the "Sasser" computer virus that crashed systems across the world, wreaking havoc in big businesses and homes.
Sven Jaschen, 19, confessed to all the charges against him when he appeared before a German court.
Katharina Kruetzfeldt, the judge at the court in the western town of Verden, said Jaschan admitted data manipulation, computer sabotage and interfering with public corporations in one of the biggest internet attacks of its kind.
After emerging around May last year, versions of the Sasser "worm", named after 1sass, the crucial Windows service it attacks, went on to knock out an estimated one million computer systems among home users and companies by spreading on the ubiquitous Microsoft Windows operating system.
Sasser victims ranged from the British Coastguard to the European Commission, Goldman Sachs and Australia's Westpac Bank. Some security firms called it the most destructive worm ever.
Silke Streichsbier, a state prosecutor, said she was "highly satisfied" with progress made at the trial, which is closed to the public as Jaschan was still a minor when some of the offences took place.
A formal verdict is expected tomorrow.
Jaschan, who had previously confessed to having created the worm to police, could face a maximum sentence of five years in prison as well as having to pay compensation to his victims.
Prosecutors said damage amounting to some €130,000 (90,000) had so far been reported by victims of the worm, but the figure could spiral into millions of pounds if everyone affected worldwide were to report financial losses caused by the worm.
How the teenager was expected to pay such compensation was not clear.
Jaschan, described by authorities as a "computer freak", was identified as the author of the virus after Microsoft offered a reward of $250,000 for information leading to his arrest.
It is believed he began creating programmes, including the Netsky virus, to seek out and destroy other viruses.
The vulnerability that Sasser exploited was first identified on 8 October, 2003, by security firm eEye Digital Security.
The virus is called a worm because it searches out machines to infect by itself without any help from users. Jaschan regularly upgraded the virus so it was able to sneak around firewalls that Micro-soft threw up with increasing desperation.
The teenager's decision to target the United States brought the FBI in on the hunt and they were instrumental in narrowing down Sasser's source before the youngster was pinpointed by an informer.
The hunt cost an estimated 5 million. After he was arrested in May last year, Jaschan revealed that all of his classmates at college knew that he was the author of the virus.
Jaschan was known as a shy, quiet teenager studying computer science at a vocational school in Rotenburg.
He discussed the Netsky worms he was creating - the forerunners to Sasser - in early 2004 with his brothers, sisters and many of his classmates.
As the various versions of the Netsky worm bombarded businesses worldwide with millions of nuisance e-mails, Jaschan finally felt he was earning the respect of his classmates. "It was just great how Netsky began to spread, and I was the hero of my class," he said.
At the end of April 2004 Jaschan released the Sasser worm, which spread quickly via the internet without using e-mail.
Shortly afterwards, Jaschan, apparently concerned about being caught by the authorities, claims he e-mailed his friends saying that he would stop writing worms, and decided to wipe parts of his hard disc and encrypt viral source codes on his computer.
In early May, one of Jaschan's schoolfriends revealed the worm author's identity to Microsoft.
The house Jaschan shared with his mother and stepfather was raided by the authorities.
Computer-crime officers searched the house, disconnecting PCs, taking photographs, and collecting CDs and floppy discs.
Realising that it was useless to deny his involvement with the worms, Jaschan told the officers the password to his encrypted files.
During interrogation Jaschan also revealed the names of friends who are said to have helped him.
Graham Cluley, a senior technology consultant for the anti-virus company Sophos, said: "It's a shame that someone with obvious computer skills should turn to writing computer viruses to increase their self- esteem, rather than doing something positive like developing computer games or an innovative website.
"It's a sad story of how a young man with potential can make the wrong decisions and end up disrupting millions of business and home computer users around the world."
As the son of a computer repair shop owner, Jaschan spent much of his time with machines and had been trying to get a job which would allow him to continue with his hobby.
Now he is facing jail when he is sentenced, although authorities indicate that leniency will be shown because of his age.