A US teenager has been arrested under suspicion of creating the Blaster or LoveSan.B virus, and court papers reveal intriguing details about the origin of the Blaster worm.

Jeffrey Lee Parson, 18, has admitted modifying the original Blaster worm using a text editor, adding a Trojan to allow backdoor access to infected computers and releasing it into the wild.

According to court papers, the original Blaster was created after a Chinese hacking collective called Xfocus reverse engineered the original Microsoft patch.

"With this arrest, we want to deliver a message to cyber-hackers here and around the world," said US Attorney John McKay in Seattle.

"Let there be no mistake about it: cyber-hacking is a crime. We will investigate, arrest and prosecute cyber-hackers."

The Blaster worm exploited a publicised Microsoft flaw that some IT managers had left unpatched.

This allowed the worm to spread without users opening attachments simply by spamming itself to large numbers of random IP addresses. Four versions have been detected in the wild.

But it seems that Parson is not the cyber-genius some US authorities are claiming.

Investigators deliberately infected a PC with Blaster.B and monitored it as it tried to contact a website to register that it had been infected. The domain was registered in his father's name.

"The antivirus community is hitting its head against the wall at how stupid this guy was," said Graham Cluley, senior analyst at antivirus specialist Sophos.

"He did know a fair bit about computers, and seems to have written a few viruses of his own, but this was minor tweaking and it led the police right to him. Then again, anyone with seven computers in the house is obviously keen."

Parson has been charged on one count of intentionally causing or attempting to cause damage to a computer. He faces a maximum of 10 years in prison and a $250,000 fine if convicted.