Iphone 5 Untethered Jailbreak
Leoma Cianchetti
An untethered jailbreak is a jailbreak wherein a user can reboot their device at will, and have their device start up with the jailbreak automatically applied without the assistance of a computer or a utility on the device.
Most untethered jailbreaks rely on vulnerabilities in the kernel and early boot process, typically using a combination of codesigning bypasses and manipulating the system into executing a binary early in the boot process (or obtaining unsigned code execution via a vulnerability in an existing startup process). Once code execution has been obtained, a kernel exploit is used in order to patch the currently loaded kernel to allow for the rootfs to be remounted as read/write, and to allow for unsigned code execution.
Older devices, such as the iPhone 3GS, iPod touch 2 (old bootrom) and earlier, have had vulnerabilities discovered in the BootROM that are able to be executed without the assistance of DFU mode (such as via a malformed image in the NOR) allowing for stages of the boot chain to be overwritten with custom code, such as a patched LLB/iBoot to allow for an unsigned kernel, and a custom boot logo. Examples of bootrom exploits that allow for untethered code execution are Pwnage, 24kpwn and alloc8.
Some jailbreaks abuse vulnerabilities in the currently installed iBoot in order to patch out signature checks or load an alternative iBoot, therefore being able to load a patched and jailbroken kernel. Very few jailbreak utilities opt to use this method, as iBoot exploits are rare to come across and are able to be patched by Apple with software updates, thereby only being able to be used if blobs have been saved, or if the device was discontinued before Apple released a patch.
iOS jailbreaking is the use of a privilege escalation exploit to remove software restrictions imposed by Apple on devices running iOS and iOS-based[a] operating systems. It is typically done through a series of kernel patches. A jailbroken device typically permits root access within the operating system and provides the right to install software unavailable through the App Store. Different devices and versions are exploited with a variety of tools. Apple views jailbreaking as a violation of the end-user license agreement and strongly cautions device owners not to try to achieve root access through the exploitation of vulnerabilities.[1]
While sometimes compared to rooting an Android device, jailbreaking bypasses several types of Apple prohibitions for the end-user. Since it includes modifying the operating system (enforced by a "locked bootloader"), installing non-officially approved (not available on the App Store) applications via sideloading, and granting the user elevated administration-level privileges (rooting), the concepts of iOS jailbreaking are therefore technically different from Android device rooting.
Expanding the feature set that Apple and its App Store have restricted is one of the motivations for jailbreaking.[2] Apple checks apps for compliance with its iOS Developer Program License Agreement[3] before accepting them for distribution in the App Store. However, the reasons for Apple to ban apps are not limited to safety and security and may be regarded as arbitrary and capricious.[4] In one case, Apple mistakenly banned an app by a Pulitzer-Winning cartoonist because it violated its developer license agreement, which specifically bans apps that "contain content that ridicules public figures."[5] To access banned apps,[6] users rely on jailbreaking to circumvent Apple's censorship of content and features. Jailbreaking permits the downloading of programs not approved by Apple,[7] such as user interface customization and tweaks.
Software programs that are available through APT or Installer.app (legacy) are not required to adhere to App Store guidelines. Most of them are not typical self-contained apps, but instead are extensions and customizations for iOS or other apps (commonly called tweaks).[8] Users can install these programs for purposes including personalization and customization of the interface using tweaks developed by developers and designers,[8] adding desired features such as access to the root file system and fixing annoyances,[9] and making development work on the device easier by providing access to the file system and command-line tools.[10][11] Many Chinese iOS device owners also jailbreak their phones to install third-party Chinese character input systems because they are easier to use than Apple's.[12]
Jailbreaking also opens the possibility for using software to unofficially unlock carrier-locked iPhones so they can be used with other carriers.[19] Software-based unlocks have been available since September 2007,[20] with each tool applying to a specific iPhone model and baseband version (or multiple models and versions).[21] This includes the iPhone 4S, iPhone 4, iPhone 3GS, and iPhone 3G models. An example of unlocking an iPhone through a Jailbreak utility would be Redsn0w. Through this software, iPhone users will be able to create a custom IPSW and unlock their device. Moreover, during the unlocking process, there are options to install Cydia the iPad baseband.
Cybercriminals may jailbreak an iPhone to install malware or target jailbroken iPhones on which malware can be installed more easily. The Italian cybersecurity company Hacking Team, which sells hacking software to law enforcement agencies, advised police to jailbreak iPhones to allow tracking software to be installed on them.[22][23]
On iOS devices, the installation of consumer software is generally restricted to installation through the App Store. Jailbreaking, therefore, allows the installation of pirated applications.[24] It has been suggested that a major motivation for Apple to prevent jailbreaking is to protect the income of its App Store, including third-party developers and allow the buildup of a sustainable market for third-party software.[25] However, the installation of pirated applications is also possible without jailbreaking, taking advantage of enterprise certificates to facilitate the distribution of modified or pirated releases of popular applications.[26]
A package manager or package-management system is a collection of software tools that automates the process of installing, upgrading, configuring, and removing computer programs. For jailbreaks, this is essential for the installation of third-party content. There are a few package managers specifically for jailbroken iOS devices, of which the most popular are Cydia, Sileo, Zebra and Installer 5.
Once a device is jailbroken, the built-in security is compromised due to the vast amount of kernel patches that go into building the tool. Security structures like Apple Mobile File Integrity, Sandbox, Read-Only Root File system, and trusted apps get disabled or otherwise tampered with, to achieve the goals of the jailbreaking tool. This, in turn, creates potential security issues for the user of a jailbroken device.
Users of a jailbroken device are also often forced to stay on an inferior iOS version that is no longer supported by Apple because newer versions usually cannot be jailbroken right away. This has the potential to introduce security issues because for these older versions there are known security vulnerabilities, exploits, and exploit proof of concepts published.
In March 2021, jailbreak developer GeoSn0w[27] released a tweak called iSecureOS which can alert the users of security issues found on their devices. The application works akin to antivirus software, in that it scans the files on the user's device and checks them against a database of known malware or unsafe repos.
In June 2021, ESET Research confirmed that malware did exist on one of the piracy repositories in the jailbreak community. The malware actively targeted iSecureOS to try to bypass the detection,[28] but updates to the security app were quickly released and have mitigated the malware.
Where Android rooting and jailbreaking are similar is that both are used to grant the owner of the device superuser system-level privileges, which may be transferred to one or more apps. However, unlike iOS phones and tablets, nearly all Android devices already offer an option to allow the user to sideload 3rd-party apps onto the device without having to install from an official source such as the Google Play store.[29] Many Android devices also provide owners the capability to modify or even replace the full operating system after unlocking the bootloader, although doing this requires a factory reset.[30][31][32]
In contrast, iOS devices are engineered with restrictions including a "locked bootloader" which can not be unlocked by the owner to modify the operating system without violating Apple's end-user license agreement. And on iOS, until 2015, while corporations could install private applications onto corporate phones, sideloading unsanctioned, 3rd-party apps onto iOS devices from sources other than the App Store was prohibited for most individual users without a purchased developer membership.[33] After 2015, the ability to install 3rd-party apps became free for all users; however, doing so requires a basic understanding of Xcode and compiling iOS apps.
Jailbreaking an iOS device to defeat all these security restrictions presents a significant technical challenge.[34] Similar to Android, alternative iOS app stores utilizing enterprise certificates are available, offering modified or pirated releases of popular applications and video games, some of which were either previously released through Cydia or are unavailable on the App Store due to these apps not complying with Apple developer guidelines.
When a jailbroken device is booting, it loads Apple's own boot software initially. The device is then exploited and the kernel is patched every time it is turned on. An untethered jailbreak is a jailbreak that does not require any assistance when it reboots up. The kernel will be patched without the help of a computer or an application.
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