PC World - Perhaps Microsoft isn't alone in issuing some security patches on the down-low. A new report from security software maker Sophos claims that Apple this week silently updated anti-malware protection in its Mac OS X operating system. In fact, the patch was so hush-hush that Apple failed to mention it in either the release notes or security bulletin that came with its Mac OS X 10.6.4 upgrade, which included the mysterious security fix.

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