Anatomy Of A Mac APT Attack

You've heard it all before: If you're a Mac, then you're immune from most of the latest security threats. That has led some organizations worried about cyberespionage-type attacks to consider ditching their target-prone Windows machines for their Mac iOS counterparts, according to a team of researchers who spoke at Black Hat USA last week in Las Vegas.

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Mac OS X might have little or no exploits aimed at it right now, but security worry-free Mac users are still susceptible to targeted attacks -- especially ones like advanced persistent threat (APT) that use social engineering, according to the researchers. A recent report by ESET found that while 52 percent of Windows users feel "extremely" or "very" vulnerable to cybercrime, only 20 percent of Mac users feel that way.

"Mac users are trained to feel safe, and they have a long history of not being exploited by attackers. They get used to clicking through unsigned apps," said Paul Youn, a researcher with iSec Partners.

And that's where the Mac's downfall could be when it comes to a targeted attack like an APT.

Youn, along with fellow iSec researchers Alex Stamos, Tom Daniels, Aaron Grattafiori, and BJ Orvis, decided to analyze just how a Mac could sustain a targeted attack by an APT attacker. "The reason we're doing this talk is because, in part, of our incident response on APT, [clients] said, 'Maybe we should switch to Macs,'" Stamos said in the team's presentation. "They asked us what would that mean for their ability to withstand those attacks. We don't know. There has been no research into this [before]."

Macs, which hold about 6 to 8 percent of the desktop market share, overall suffer fewer threats and attacks, and no popular crimeware kits are available for Mac OS 10. "There are a lot of things that makes Mac users much safer than Windows users," Youn said. So far, Mac attacks have mainly been social engineering-based, such as the recent Mac Defender fake antivirus scam, he said.

But the Mac OS has plenty of vulnerabilities that are ripe for attackers' picking, even if they haven't been exploited yet, according to the researchers. A 2008 IBM X-Force report showed that OS 10 had 14.3 vulnerabilities -- more than any other operating system -- and Apple's latest OS X patch included 39 CVEs. "They may be safer, but that doesn't mean the OS is more secure," Youn said. "Malware can exist on an OS 10, and Mac users may be susceptible to social engineering.

APT attackers don't care what OS a target is running: "That the typical Mac user doesn't get hit often has no bearing on the APT," he said. "There are plenty of vulnerabilities that could be weaponized to exploit Mac users if someone bothered to do it."

And unlike with Windows, few tools are available for conducting a forensics investigation on Macs. Chester Wisniewski, senior security adviser at Sophos Canada, says even if you want to investigate a breach on a Mac platform, that can be difficult. "OS 10 is just starting to get tools," he says. "There's a lack of mature tools for Mac OS X forensics."

InfoSec Partners' Stamos says the key with APT-style attacks is being able to see and analyze what has hit the victim machines. "There's no good way to check the integrity of a Mac when it gets hit," he said.

Among the weaknesses in the Mac that could be used for a targeted attack are the lack of a standardized authentication mechanism; authentication weaknesses in AFP, OpenDirectory, and ServerAdmin; and that Bonjour can make local DNS poisoning a fairly simple attack, the researchers said. Local and network privilege escalation is easy to accomplish, they said.

A copy of their presentation, "Macs In the Age Of APT," is available here (PDF) for download.

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