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.
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