Japanese malware author admits guilt

Movie-munch miscreant on trial for copyright infringement

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A Japanese man has confessed to creating a data-destroying Trojan horse.

Masato Nakatsuji, 24, admitted in Kyoto District Court that he wrote a Trojan horse that incorporated copyrighted animation footage as a lure. The booby trapped file was distributed via the controversial Winny filesharing system in Japan last year.

Surfers who fell for the bait and opened the file risked finding their Windows PC infected with malware, identified by anti-virus firms as the Pirlames Trojan, that wiped music and movie files from compromised systems.

Two other men were also arrested alongside Nakatsuji, but are yet to stand trial

Nakatsuji admitted writing the malware during the first day of his trial on Tuesday, where he faces charges of copyright infringement and defaming an acquaintance by embedding his photograph within the malicious code. Oddly, he isn't being tried for virus writing.

Nakatsuji's defence team argues that the malware created by Nakatsuji caused little damage and that the interests of justice would not be served by imprisoning the graduate student for distributing a Trojan horse when there were no specific laws against it, English language Japanese daily The Yomiuri Shimbun reports.

Security watchers say Japan ought to consider drafting specific legislation clearly outlawing virus creation, currently something of a grey area in Japanese law. This legislative gap is unlikely to help Nakatsuji.

"If he is found guilty, the general public are unlikely to worry that it was his ill-advised choice of graphics which got him into legal trouble rather than virus-writing," said Graham Cluley, senior technology consultant for Sophos.

The Pirlames Trojan is far from the first time the Winny filesharing network has been linked to malware-related security snafus. In May 2006, a virus was blamed for leaking power plant secrets via Winny for the second time in four months.

A month earlier, a Japanese anti-virus company was embarrassingly forced to concede that internal documents and customer information were leaked onto Winny after one of its workers failed to install anti-virus software.

Nakatsuji himself is in much the same trouble as Isamu Kaneko, the author of the Winny filesharing program. Kaneko was also charged with copyright violation in a case that ultimately resulted in a fine.

The case against Nakatsuji continues. ®

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