Japanese authorities have arrested their first virus writer, but only for breaching copyright.
It is not illegal to write a computer virus in Japan, but the authorities there have arrested three men alleged to have been involved in a plot to infect users of the Winny file-sharing network.
Police in Kyoto made the arrests after a Trojan horse on the network displayed images of popular anime characters while wiping MP3 and movie files.
The malware has been dubbed "Harada" in media reports, and is believed to be related to the Pirlames Trojan horse which appeared last year.
One of the men is alleged to have written the malware, while the other two are believed to have distributed the malicious code via Winny.
"It is not illegal to write viruses in Japan, so the author of the Trojan horse has been arrested for breaching copyright because he used cartoon graphics without permission in his malware," said Graham Cluley, senior technology consultant at web security firm Sophos.
"Because this is the first arrest in Japan of a virus writer, it is likely to generate a lot of attention and there may be calls for cybercrime laws to be made tighter," he said.