How to secure Macs in business

Security flaw No. 4: Naïve use of Back to My Mac

Mac OS X includes one special service that sounds alarming at first glance -- and can be a real security hole in unmanaged environments. Back to My Mac, a remote access system built into Mac OS X 10.5, requires both a MobileMe account (formerly .Mac) from Apple and administrator privileges. Back to My Mac operates like the GoToMyPC familiar to Windows administrators, although it's less insistent about working around intentional blockades.

While Apple uses IPv6 tunnels, IPsec encryption, and Kerberos tickets to secure connections, starting up such a connection from anywhere on the Internet requires just the password to someone's MobileMe account. With that password, all computers with Back to My Mac enabled can have their files examined or screens remotely controlled.

In a managed enterprise, security experts don't believe that Back to My Mac creates any real risk, despite its feature set. "No enterprise is going to allow something like Back to My Mac unless it's running through a VPN tunnel," Mogull says, at which point it would conform to the enterprise's policy. If users are running Back to My Mac on their own, "it would mean that [IT] royally screwed up" the firewall, he adds.

Matasano Chargen's Ptacek says that Back to My Mac will eventually fall under the category of services that businesses ban their employees from using in the office. "Enterprise users are not allowed to use Gmail or Yahoo Mail," he notes, and Back to My Mac should be treated the same.

Solution: Confirm that Back to My Mac won't work in your environment. Establish a policy that bans its use.

Security flaw No. 5: Complacency over malware

The recent appearance of a kit that lets malicious parties install Trojan horses in legitimate software to, in turn, obtain root access to a Mac seems to run counter to the widely held view that Macs are immune from many of the exploits that once plagued Windows (and that Vista has ameliorated).

But that Trojan horse doesn't meet the smell test: Like a few other "concept attacks," the exploit requires that someone download and install software, although no password is required for the malware to run. (The exploit relies on the escalated privileges available for the Apple Remote Desktop agent, or ARDAgent, even when it's turned off. An AppleScript command can be sent to the agent, which is handed off as a root-level shell command.) A survey of security experts and the buzz among the Mac enterprise management community shows that this threat is a nonstarter.

The fact is that the Mac has not been a malware target, and it is safer than Windows from such threats. And that's where the risk lies: The Mac is safer from malware today, and there's very little concern about the Mac being a gateway to infecting Windows users.

But that may not be true in the future, and there is some concern that IT won't be ready to protect Macs from malware when that day comes.

Today most of those who follow Mac security closely seem to abjure anti-virus software. "It's not unreasonable to use anti-virus in an enterprise, especially if compliance is an issue," says Mogull -- but "I wouldn't necessarily recommend that for a consumer," he adds, because today's anti-virus apps don't address Mac OS X's actual risk profile today. "Anti-virus is an industry failure," Ptacek says. Because of this, he can't recommend that companies install anti-virus software at all.

Dino Dai Zovi, an independent security researcher, is concerned about acceleration in this area. "Because there is still very little malware in the wild targeting Apple, it is still a safe platform, and it is in a lot of ways safer than the Windows equivalent. But I think that that time is rapidly changing," he says.

Mogull cautioned that the worst could be yet to come. "It isn't that the Mac is immune or even more resistant to these attacks, there just hasn't been very much interest in them," he says, a sentiment echoed by security experts and IT managers. With more Macs in the enterprise, it's likely that attacks designed to extract information or take over Macs to use them as zombies will hit the wild.

While the Mac OS itself is fairly safe, at least for now, from malware, the Mac OS X's default Safari browser is not. "We've long since moved into this place where it's about the browser and about JavaScript," Ptacek says.

Even security experts unconcerned over OS-level malware threats are worried about browser-based threats. The fears center on as-yet-undiscovered flaws in the Safari browser and on Apple's use of the Webkit, a browser engine that's both employed throughout OS X and available to third-party developers. The concerns are not theoretical: A flaw in Safari on the iPhone found in a TIFF library module lets an iPhone forfeit root control just by visiting a Web page. (This was briefly a popular way of jailbreaking iPhones to install third-party software.)

Solutions:Keep abreast of security updates and security news related to Macs. Make sure the same outgoing firewall monitoring tools cover Macs as other platforms to identify hallmarks of hijacked systems.

Security flaw No. 6: Apple's security is half-baked

The strongest concerns over Mac OS X security have to do with improvements introduced in Mac OS X 10.5 (Leopard) that fall short of what's fully needed. "Nothing in Leopard is completely implemented," says Mogull. "They finished enough to get their marketing bullet point, but not a real strong level of defense," concurs Dai Zovi.

Leopard has a strong foundation on which more enterprise-oriented features should be built, as well as a greater extension of integrity and attack resistance for individual users on their own or in companies. For example, Apple added library randomization to Mac OS X 10.5, which prevents virus writers from finding code at specific places in memory each time. However, unlike with Vista, only a subset of what can be protected is actually protected.

Some suspect that Apple will finish building enterprise-class security in Snow Leopard, the next major Mac OS X, slated for summer 2009. While Apple is scant on details related to Snow Leopard, it's clear that with the "pause button" pressed, as Apple CEO Steve Jobs put it, security and enterprise support will be two of the big improvements expected. (Better use of multiple cores and processors and a push toward optimized software such as JavaScript and QuickTime will be two of the other pillars.)

Solution: With Snow Leopard a year away, security-conscious enterprise may choose to delay serious Mac deployments until they know precisely what security improvements Apple commits to for that release.

Don't be complacent about Mac security

It's vital that security planning takes place before holes appear, and that the IT staff is ready to handle the differences between the Windows, Unix, and Linux systems they may be accustomed to and what Mac OS X brings with it.

Dai Zovi said, "The biggest danger is a sense of complacency: 'Oh, it's a Mac, we don't need to worry about this.' "

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