China is putting more effort into its cyberwar capabilities. Many of the Chinese spies detected in the United States have been seeking information that would assist a cyberwar attack via the Internet. An increasing number of prominent Chinese hackers (or honkers as they call themselves) are disappearing into government and military organizations known to be fronts for cyberwar research. Individuals and organizations thought to be representing China have been showing on the Internet underground, offering good prices for exploits (flaws in Internet software that can allow hackers to secretly enter, or even take over, PCs connected to the Internet.) China also buys exploit information from legitimate computer security firms, but does it through front corporations. These exploits are the raw material cyberwarriors use to built cyberwar weapons. Most exploits have a short shelf life, for once the software manufacturer knows of the problem, they fix it. But in the weeks or months it takes for the flaw to be fixed, computers using the affected software are vulnerable. Even after software patches have been issued, it takes months before the majority of users fix their software, and some users never get around to fixing the problems until they upgrade to a new version of the software, or otherwise stop using it. China is also making itself less vulnerable to these weapons by switching from the use of Microsoft software (which has the most exploits available) for Linux (which has much less vulnerability.) Microsoft is the most vulnerable because, world wide, it is used on 90 percent of PCs. Linux does not have as much specialized software available for it, but this is not a problem for most government and commercial users in China. This shift from Microsoft to Linux has been going on for nearly five years, and most new software written in China is for Linux, not Microsoft, systems.