Is a jailbroken iPhone for you?
The "evad3rs" team has published its "evasi0n" jailbreak tool (for free) to the iOS community. The team claims that in roughly a week, some 7 million users have used the tool to jailbreak their iOS devices. By any measure, the launch -- already up to Version 1.3 to support Apple's iOS 6.1.1 release on iPhone 4Ses -- has been wildly successful.
But is jailbreaking your device something you want to do? Let's consider a few issues before you dive in.
First, just what is jailbreaking? It's the process of removing the sandbox protections that Apple places in its iOS products. Its purpose is primarily to enable users to install unreviewed (by Apple) software on their iOS devices. Secondarily, it enables users to access files they normally wouldn't be permitted to, which opens up all sorts of possibilities for customizing an iOS system. Many technically inclined users find liberation in these things and loathe being locked into a sandboxed device.
There are entire unsupported (again, by Apple) communities where apps can be purchased or simply acquired for free. These communities don't have the strict curation policies that Apple employs in its App Store, and that is exactly its appeal to the jailbreakers. Indeed, many apps that were rejected by Apple over some policy violation or another have ended up in the jailbreak app communities.
Is it legal? Apparently it is, at least in the U.S. In 2010, the U.S. Copyright Office declared jailbreaking to be an exception to the Digital Millennium Copyright Act. But the situation is not exactly cut and dried. See here for more information, but it seems that jailbreaking an iPhone in the U.S. remains legal, while doing the same to an iPad is not. The bottom line is this: if you're at all concerned about the legality of jailbreaking your device, you're probably well advised to abstain. And be aware too that Apple maintains that jailbreaking may well void a device's warranty.
Is it safe? The answer probably has more to do with you than with anything else. Most jailbreaks completely remove iOS's app sandboxing features, even after the device has been booted up after the jailbreak process itself. At this point, all apps essentially run in a privilege state where they can all read/write pretty much anywhere on the device. This opens up a jailbroken device to possible malware, data exfiltration and so on. Essentially, a jailbroken device has all the file protections of a Windows 3.1 system. It's a single-user device, and every app can get to everything.
This is one of the aspects that appeal to many jailbreakers, but for the masses, jailbreaking can be a pretty reckless act. After all, nearly five years after Apple launched its App Store, we have zero in-the-wild malware samples on non-jailbroken iOS devices. Meanwhile, several malware incidents have occurred in the jailbroken app community, including at least one worm that exploited a default sshd password to copy itself among jailbroken iOS devices.
Now, this falls far short of being a condemnation of the underground app ecosystem, but if that community continues to proliferate as we've seen in the Android community, it's quite possible things will get worse. Numerous recent studies of Android apps have documented massive increases in malware in that community. Let's hope that's not the future for the jailbroken iOS app world.
All of this is why I say that who you are is what will ultimately guide you to deciding whether jailbreaking your iPhone is a wise thing to do. If you're among the tech-savvy, you've probably already made that choice. If you're on the fence, chances are the best answer is no. There is a burden that comes with jailbreaking your device. You need to exercise hyper caution in allowing apps into your now unprotected environment. A mistake here can be costly indeed. But if you're willing to accept that risk and the consequences of failure, have at it.
That said, there are a few use cases that bear further consideration. If you're an app developer, jailbreaking a test machine can be worthwhile. By doing so, you can accurately peruse the entire filesystem for data leakages, such as the spell checker key log, the cut-and-paste buffer and so forth. These data stores are normally off-limits, but if you truly want to understand the security risks posed by your own software, there's no substitute for seeing these things firsthand.
Also, if a jailbroken device is lost or stolen, you can pretty comprehensively understand what data may have been exposed, because you will be able to pore through all the other data stores on the device, such as the SMS/iMessage texts, address book, calendar, some (but not all) keychain items, and other system files that you'd normally be prohibited from exploring forensically. (You would do this by restoring from backup the data from the missing device onto a replacement device, which you would then jailbreak.) That can help you determine the risk exposure after a device has gone missing. Be warned that this process is time-consuming and costly, but in some cases it will be worth the effort.
The bottom line is that jailbreaking can be exhilarating and liberating, but it shouldn't be done by anyone who isn't willing to swim in an open sea of noncurated apps. For the vast majority of users, this translates to unnecessary and unjustifiable risks. Just walk on by.
With more than 20 years in the information security field, Kenneth van Wyk has worked at Carnegie Mellon University's CERT/CC, the U.S. Deptartment of Defense, Para-Protect and others. He has published two books on information security and is working on a third. He is the president and principal consultant at KRvW Associates LLC in Alexandria, Va.