One of the jibes about GNU/Linux from the closed-source crowd is that the only reason there so few security exploits against it is that its market share is too small for crackers to care. Against that background, the following development must represent some kind of milestone:

The art of burying invisible malware deep inside a Linux machine is about to go mainstream, thanks to a new open-source rootkit released Thursday by Immunity Inc., a firm that supplies tools for penetration testers.

When implemented, Immunity's DR, or Debug Register, makes backdoors and other types of malware extremely difficult to detect or eradicate. It's notable because it cloaks itself by burrowing deep inside a server's processor and availing itself of debugging mechanisms available in Intel's chip architecture. The rootkit, in other words, mimics a kernel debugger.

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