The Japanese authorities have tested a 'virus' cyberweapon capable of tracing and disabling computers being used in cyberattacks against the country, a newspaper in the country has reported.
Quoting anonymous sources said to be connected to the project, The Yomiuri Shimbun said that Japan's Defense Ministry's Technical Research and Development Institute began developing the program three years ago in conjunction with Fujitsu, since when it had been tested on a closed network.
What they've ended up with sounds like the first of a type of multipurpose program many experts suspect other countries are also developing, namely one capable of quickly identifying the chain of servers and computers being used in different types of cyberattack scenario.
These would include DDoS attacks, those in which a large number of computers are used to attack a company's or country's computing infrastructure, but also subtler attacks designed to steal data.
In either case the program is described as being able to disable an attacking resource, which is probably where the trouble starts from a Japanese legal standpoint.
The country has strict laws on producing programs that could be construed as malware let alone wielding them in a cyberwar context that inevitably blurs the distinction between defence and attack.
It is generally assumed that all countries (especially the US and its allies that had previously taken a benign view of the Internet) are developing programs for cyber-defence and offence. These are almost never talked about beyond a few veiled references in speeches by senior politicians.
This has begun to change very slowly in the aftermath of 2010's Stuxnet affair, a program believed on the basis of circumstantial evidence to have been created with the sole purpose of attacking Iran's nuclear program.
Japan's willingness to drop hints about its plans might have something to do with a recent spate of attacks on the country's Government infrastructure. These include attacks on the country's defence contractors, its politicians, and leading industrial sectors.