Mac Security After Flashback: 5 Key Points

Are Macs being more actively attacked?

In the wake of the Flashback malware outbreak that successfully infected over 600,000 Macs, security watchers have declared that cyber-crime rings and nation states have begun to more actively target Macs.

"Recently, malware that targets Mac computers, such as OSX.Flashback and OSX.Sabpab, are increasing," read a blog post from Symantec. "This recent increase provides evidence that malware authors now consider Mac computers a viable battleground along with the Windows platform."

Just how bad is the security situation? Here are five related facts:

1. Flashback infections remain high. Symantec has said that the Flashback eradication campaign has been slower than expected. While over 600,000 machines were infected at one point, by Wednesday that number had dropped to less than 100,000, said Symantec. But Russian security firm Doctor Web, which discovered the malware on April 4, 2012, said that a TCP handshake problem with the sinkhole that Symantec is using to study the malware had led to undercounting. According to Doctor Web, by Thursday there were still at least 566,773 Macs infected with Flashback.

2. Security vendor predicted outbreak. Interestingly, before the widespread Flashback outbreak, F-Secure observed an earlier version of the malware, which targeted old Java vulnerabilities. "We might begin seeing a real OS X outbreak if the gang upgrades their operation a notch higher and start targeting unpatched vulnerabilities," said the F-Secure analysis. Shortly thereafter, of course, Flashback's authors got their hands on the Java zero-day vulnerability and went to town.

[ For more background on the Mac Flashback attack, see Apple Mac Attack Began With Infected WordPress Sites. ]

3. Disabling Java blocks many Mac threats. Before the mass outbreak, the F-Secure analysis had also advised Mac users that "the easiest way to avoid infection"--from malware such as Flashback--"is to just disable Java from your browser(s)." It said that based on its user surveys, most people simply don't need Java to browse the Web. Not long after the Flashback outbreak, meanwhile, what did Apple do? First, it responded with operating system upgrades that patched the Java vulnerability exploited by Flashback. But it also tweaked Java for OS X 10.7 to deactivate itself if not used for 35 days.

4. Most malware on Macs runs on Windows. "One in five Macs has malware on it. Does yours?" trumpeted the headline of a recent Sophos blog. But as anyone who's installed Mac antivirus has probably learned, almost all the malware spotted by such software infects only Windows PCs. In fact, that's the exact finding of the Sophos survey, which is based on 100,000 users of its free Mac OS X antivirus software. Notably, Sophos found that only 2.7% of all scanned Macs harbored Mac-compatible malware, adware, or other suspicious software. (In comparison, some studies that estimate that nearly half of all Windows machines harbor such software.)

5. Targeted attacks still hitting Macs. Earlier this month, Trend Micro detailed a new targeted attack with an unusual twist: the ability to infect both PCs and Macs. The attack begins with social engineering: an email with pro-Tibetan sentiments that includes a link. Clicking on the link leads to a website script that determines whether the system is running a Windows or Mac operating system. At that point, the script pushes a Java applet--designed for the correct operating environment--that breaks out of the Java sandbox, then installs a Trojan application that provides backdoor access to the machine.

While the two Trojans are written in different languages--Python for Macs, and a Windows executable for Windows PCs--the infection results appear to be the same. "Both backdoors report back to the same C&C server," reported Trend Micro. "Moreover, both backdoors have functionalities that include features to allow them to upload and download files and navigate through files and directories in the affected system, providing them further means for their lateral movement and data exfiltration activities."

In other words, attackers do appear to now be paying more attention to Macs.

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