Mac OS Becoming Juicier Target for Virus Writers

Compared with Windows, the Macintosh platform is still largely untouched by vulnerability exploits.

But the prompt release of exploit code for a vulnerability detailed in a May 24 set of updates shows that it's catching up fast when it comes to grabbing the attention of exploit writers.

"It is very Microsoft. It's something we've grown to expect in Microsoft: The descriptions of patches lead people to write exploits for something that's been patched," said Rob Enderle, principal analyst for the Enderle Group. "It was only a matter of time before that kind of behavior hit [the Mac] platform. People are going after consumers, and they're going after consumers broadly."

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Security research company Immunity released the exploit code — which leveraged a buffer overflow vulnerability in the UPnP Internet Gateway Device Standardized Device Control code that's used to create port mappings on home NAT (Network Address Translation) gateways in the OS X mDNSResponder implementation — less than 24 hours after Apple had released a patch for it.

Apple implements the protocol in its Bonjour technology to enable devices to automatically discover each other without users having to enter IP addresses or configure DNS servers.

The release of the exploit code for this flaw shows that interest in Mac vulnerabilities is high, analysts say.

That's not surprising; even though Macs aren't used as broadly in businesses as Windows machines, plenty of consumers use them, Enderle said.

Another factor that may be causing attackers to focus more on Macs is that Windows operating systems are getting "much [harder] to penetrate," he said.

And to top it all off, Mac users constitute a "relatively lucrative demographic."

"These aren't bottom-feeding notebook buyers," he said. "In overall terms, their number is small. But it's always been an attractive target, increasingly so since [Macs] lack secondary protections that Windows [users] enjoy [such as a rich selection of third-party security software], though the primary platform itself [has been] in many cases and still is more secure."

At any rate, as pointed out by Ray Wagner, an analyst at Gartner, nobody ever said OS X was impregnable.

"Any large code base has vulnerabilities," he said.

So no, security analysts aren't heading for the hills over the specter of attackers paying more attention to the Mac platform.

Rich Mogull, another Gartner analyst, said that the buzz in the hacker underground is that "the bad guys are targeting Macs a little more [but] not enough to be worried about yet."

Besides, one has to question the motivations behind the release of Mac exploit code, Wagner said.

"Often the motivation is some kind of publicity," he said. "Recognizing vulnerabilities in OS X does have some cachet these days."

Still, many analysts would like Apple to get more serious about security.

"Apple is as much out of touch as Microsoft was half a decade ago," Enderle said, pointing to the fact that Apple has no chief security officer. "Everybody has to take security seriously. There's no Switzerland when it comes to attacks. If you have something somebody wants they're going to find a way to get it."

Another thing that analysts fault is Apple's lack of a solid patch process — one that's regularly scheduled, such as Microsoft's Patch Tuesday or Oracle's tri-monthly patch releases.

"To date [Apple isn't] warning users much about problems and exposures," Enderle said. "[It's] kind of easing into this, not embracing a security ecosystem that lets people get ahead of the curve and take care of problems before they occur. ... [It tackles] individual problems and [it thinks that] if it fixes a given problem it will go away."

Mogull credits Apple with being increasingly responsive with putting out patches, in spite of not having a process as formalized as Microsoft's.

Still, he said, there are things Apple should be doing to its operating system that would help to secure it.

One such thing analysts would like to see in a Mac operating system is ASLR (address space layout randomization)—a technology designed to allocate random space for memory, thus making it harder for an attacker to figure out addresses of critical functions and hence harder to get exploits running correctly.

Microsoft implemented ASLR in Vista.

Although Symantec discovered that ASLR's shuffling of the address space deck, randomly locating programs in memory, wasn't as random as expected, this technique of memory handling is one of multiple security enhancements in Vista that early adopters cite as their No. 1 reason to deploy the new operating system.

But although Apple hasn't yet implemented ASLR, it has in fact recently added NX (No eXecute) bit to its memory handling in Mac OS X for Intel (from version 10.4.4 onwards), Mogull noted.

Sections of memory flagged with the NX bit attribute can only be used for storing data, meaning that commands shouldn't reside there and can't be executed if they do.

This prevents attackers from exploiting buffer overflows, during which memory overflows and overwrites some areas in memory that can be executable. (An attacker exploiting a buffer overflow sends commands to memory that are supposed to hold data, but since the processor can't tell the difference, it runs the commands instead.)

"[Famed hacker] HD Moore [and his ilk] can get around that stuff. I sure can't," Mogull said. "But it does offer extra protection."

But there are also some services running on OS X that can be exploited, Mogull said.

Input Managers in particular are well-known to be security flaws in Macs. An Input Manager is an aspect of text input, enabling such things as the entry of non-Arabic numbers.

But, as Matt Neuberg, a blogger on the Mac Internet community forum TidBITS, pointed out, the trouble is that input managers inject themselves into every application as it starts up.

"Thus an Input Manager is a general, legal method to modify application behavior," Neuberg writes. "Naturally it didn't take long for the thought to occur to someone that such modification need have nothing to do [with] inputting text! Thus, Input Managers—or, at least, bundles of code installed in a Library's InputManagers folder—are the basis of many popular hacks, including StuffIt Deluxe's MagicMenu feature, CocoaGestures, Smart Crash Reports, certain Growl Extras, PithHelmet (and SIMBL), Saft, Inquisitor, and many others (as those last examples show, this is a particularly popular way to hack Safari)."

Input Managers were also used as part of one bug featured in the Month of Apple Bugs, on Jan. 22, 2007.

Mogull is hearing that Input Managers, which allow attackers to execute arbitrary code when applications launch, will be locked down when Apple ships its next version.

At any rate, in spite of what Apple still hasn't done with regard to security, there are Mac exploits, but there are no mass Mac exploits.

Is this merely a function of Apple's small market share? Mogull grants that yes, the security shortcomings he sees in Mac OS X would mean that Apple might be having some problems if it had Microsoft's market share.

Still, it's a pretty secure platform, he said. "It's not like it's wide open."

Even after the CanSecWest security conference, when hackers broke into a Mac in a Pwn-2-Own contest, Apple had the vulnerability patched within eight days, he noted.

"Macs are not the bastions of security a lot of people would have you believe, but it's not like Apple's doing everything wrong, like some of the hacker types would have you believe," Mogull said.

Still, it will be a good day when the company gets its first CSO, he said.

"If we saw Apple getting up and warning people about things people are using to penetrate [its operating system], and talking about practices beyond patching, and embracing Symantec [and its Macintosh security products] instead of treating them like you would any other evil," it would all be for the good, he said.

"At some point you have to step up to full responsibility of protecting your platform, and that means being aggressive about protection."

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