Japanese virus writer arrested.. again

Ika Tako icon
According to media reports, a previously convicted Japanese virus writer has been arrested over allegations that he has again distributed a virus.

27-year-old Masato Nakatsuji is accused of writing malware known locally as “ika-tako” (squid-octopus) which was spread via the Winny peer-to-peer file-sharing network, changing the icons of infected computers to those of an orange cartoon octopus.

Nakatsuji is said to have told investigating police officers that he infected approximately 50,000 computers with the malware.

What’s particularly fascinating about this case is that this isn’t the first time that Masato Nakatsuji’s has caught the attention of the computer crime authorities.

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Back in 2008, Nakatsuji became the first virus writer ever arrested in Japan after distributing the Pirlames Trojan (dubbed “Harada” in the local press) via Winny that displayed images of popular anime characters while wiping music and movie files.

As a result of that earlier incident, Nakatsuji was sentenced to two years in prison, suspended for three years. If found guilty of this latest attack it is unlikely that the court will look favourably on a repeat offender.

By the way, before you ask – I’m not sure what Sophos detects the “ika-tako” malware as (or indeed, if we detect it at all). With 60,000 new examples of malware being seen by our labs every day it can be tricky to know if we detect a particular sample if all we have to go in is a name that appears to have been given to it by the newspapers.

But if I find out I’ll let you know. :)


Graham Cluley is an award-winning keynote speaker who has given presentations around the world about cybersecurity, hackers, and online privacy. A veteran of the computer security industry since the early 1990s, he wrote the first ever version of Dr Solomon's Anti-Virus Toolkit for Windows, makes regular media appearances, and is the co-host of the popular "The AI Fix" and "Smashing Security" podcasts. Follow him on Bluesky and Mastodon, or drop him an email.

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