iOS jailbreaking is the process of removing the limitations on Apple devices running the iOS operating system through the use of software and hardware exploits – such devices include the iPhone, iPod touch, iPad, and second generation Apple TV.
Jailbreaking permits root access to the iOS operating system, allowing the download of additional applications, extensions, and themes that are unavailable through the official Apple App Store. Jailbreaking is a form of privilege escalation and the term has been used to describe privilege escalation on devices by other manufacturers as well.The name refers to breaking the device out of its "jail"which is a technical term used in Unix-style systems, for example in the term "FreeBSD jail". A jailbroken iPhone, iPod touch, or iPad running iOS can still use the App Store, iTunes, and other normal functions, such as making telephone calls.
Restoring a device with iTunes removes the jailbreak.
Unlike rooting an Android device, jailbreaking is necessary if the user intends to run software not authorized by Apple. The legality of jailbreaking depends on countries and conditions.
Security, privacy, and stability
The first iPhone worm, iKee, appeared in early November 2009, created by 21-year-old Australian student Ashley Towns of Wollongong. He told Australian media that he created the worm to raise awareness of security issues: jailbreaking allows users to install an SSH service, which those users can leave in the default unsecure state. In the same month, F-Secure reported on a new malicious worm compromising bank transactions from jailbroken phones in the Netherlands, similarly affecting devices where the owner had installed SSH without changing the default password.
A Forbes staff analyzed UCSB study on 1407 free programs available from a third party source and Apple. Of the 1,407 free apps investigated in the cited study, 825 were downloaded from Apple’s App Store using the website App Tracker, and 526 from BigBoss(Cydia's default repository). 21% of official apps tested leaked device ID and 4% leaked location. Unofficial apps leaked 4% and 0.2% respectively. 0.2% of apps from Cydia leaked photos and browsing history, while the Apple store leaked none. He commented that unauthorized apps tend to respect privacy better than official ones. Also, there is a program called PrivaCy which allows user to control the upload of usage statistics to remote servers.
Installing software published outside the App Store has the potential to affect battery life and system stability if the software is poorly optimized or frequently uses resource-draining services (such as 3G or Wi-Fi).