A posting from Cnet  News in there Security and Privacy Section:

Security researchers have found a proof-of-concept attack that appears to be the first true viral malware approach for compromising OS X.

The malware is called “Clampzok.A” and is a cross-platform malware package that alters the binary files on an affected system so when executed, the binary will infect neighboring binary files.

The malware is written in assembly code, and was originally released in 2006 for Windows and Linux systems, but was recently updated to affect 32-bit Mach-O binary files in OS X machines.

Unlike Trojan horses, spyware, and adware that hide in one location on the system and persistently run to steal information or otherwise be a nuisance, viral malware attempts to spread itself around the system. Of these, a form known as a worm will try to replicate itself, but does not infect otherwise healthy files. The classic virus, by contrast, will inject itself into the compiled code of an executable or into the structure of a file, modifying it significantly so that when the file is read, the virus is executed and further injects itself around the system, wreaking havoc on the system’s ability to function.

This latest malware shows promise to do just that.

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