Snow Leopard Users Most Prone to Flashback Infection

Via Computerworld.com -

Of the Macs that have been infected by the Flashback malware, nearly two-thirds are running OS X 10.6, better known as Snow Leopard, a Russian antivirus company said Friday.

Doctor Web, which earlier this month was the first to report the largest-ever malware attack against Apple Macs, mined data it's intercepted from compromised computers to come up with its findings.

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In a Friday blog post, Doctor Web published an analysis of the communications between 95,000 Flashback-infected Macs and the sinkholed domains. Those communication attempts took place on April 13, more than a week after Doctor Web broke the news of the botnet's massive size.

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Not surprisingly, 63.4% of the Flashback-infected machines identified themselves as running OS X 10.6, or Snow Leopard, the newest version of Apple's operating system that comes with Java.

Snow Leopard accounted for the largest share of OS X last month, according to metrics company Net Applications, making it the prime target of Flashback.

Leopard, or OS X 10.5, is the second-most-common Flashback-infected operating system, said Doctor Web: 25.5% of the 95,000 Macs harboring the malware ran that 2007 edition.

Apple bundled Java with Leopard as well, but unlike Snow Leopard and Lion, it no longer ships security updates for the OS, and so has not updated Java on those Macs.

Last month, Leopard powered 13.6% of all Macs.

But while Snow Leopard's and Leopard's infection rates are higher than their usage shares, the opposite's true of OS X 10.7, or Lion. The 2011 OS accounted for 39.6% of all copies of OS X used last month, yet represented only 11.2% of the Flashback-compromised Macs.

Doctor Web did not connect those dots in its analysis, but the numbers make clear that versions of Mac OS X that included Java -- Snow Leopard and Leopard -- are much more likely to be infected by Flashback. Conversely, Lion -- by default, sans Java -- is significantly more resistant to the malware.

The Russian company's data also showed that many Mac users don't keep their machines up-to-date, something ZDNet blogger Ed Bott noted on Friday.

Twenty-four percent of the Snow Leopard-infected Macs were at least one update behind, 10.4% were three or more behind, and 8.5% were four or more behind.

Lion users were no better patch practitioners: 28% were one or more updates behind.

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To protect Snow Leopard and Lion systems from the Java-exploiting Flashback, users should launch Software Update from the Apple menu and download this month's Java updates. Software Update will also serve the newest version of those operating systems to Macs running outdated editions.

People running Leopard can disable Java in their browser(s) to stymie attacks.

Later this year, Oracle will release Java 7 for OS X. Mac users who upgrade to Java 7 will then receive security updates directly from Oracle, not from Apple.