Differences between Tethered Jailbreak and Untethered Jailbreak
Contents
Comparison Article[edit]
Jailbreaking is the process of removing software restrictions imposed by Apple on devices running the iOS, iPadOS, tvOS, and watchOS operating systems. This privilege escalation allows root access to the file system, enabling the installation of applications, themes, and tweaks unavailable through the official App Store. The primary distinction between jailbreak types is the method required to reboot the device and whether the jailbroken state persists after a power cycle.
Comparison of tethered and untethered jailbreaks[edit]
Jailbreaks are categorized by their persistence and the requirements for the initial boot sequence. A tethered jailbreak relies on a connection to an external computer to complete the boot process. An untethered jailbreak allows the device to boot into a jailbroken state independently.
Tethered jailbreak[edit]
A tethered jailbreak requires a USB connection to a computer every time the device is powered on. A desktop utility must "push" the necessary patches to the device to allow it to boot past the Apple logo. If the device restarts or the battery dies without a computer nearby, it remains in a non-functional state or enters recovery mode.
These jailbreaks often utilize hardware vulnerabilities in the BootROM (Boot Read-Only Memory). Because the BootROM is hardware-based, the vulnerability cannot be patched by Apple through software updates. An example of this is the "checkm8" exploit, which affects devices with A5 through A11 chips.
Untethered jailbreak[edit]
An untethered jailbreak is the most convenient for the user. Once the device is jailbroken, it can be rebooted at any time without external hardware. The exploit chain is designed to run automatically during the boot sequence.
Developing an untethered jailbreak is complex because it requires multiple vulnerabilities to bypass various layers of the iOS security stack, including Kernel Patch Protection (KPP) or Kernel PAC (Pointer Authentication Code). Untethered jailbreaks have become increasingly rare on modern iOS versions as Apple has hardened the boot chain.
Comparison table[edit]
| Feature | Tethered Jailbreak | Untethered Jailbreak |
|---|---|---|
| Lost upon reboot | Permanent until restored | ||
| Connection to computer via USB | No external hardware needed | ||
| Often uses BootROM exploits | Usually uses software-level kernel exploits | ||
| Low; device is unusable if it reboots | High; functions like a stock device | ||
| Often unpatchable via software | Patchable via iOS updates | ||
| Limited to older hardware | Very rare for current iOS versions | ||
| Uses DFU mode for patching | Installed via app or web browser |
Related variants[edit]
While tethered and untethered were the primary categories in early iOS history, two intermediate types emerged as security increased:
- **Semi-tethered**: The device can boot without a computer, but jailbreak features (like Cydia) do not work. A computer is required to re-enable the jailbreak.
- **Semi-untethered**: The device boots normally into a stock state. The jailbreak is re-enabled by running an application on the device itself, such as Unc0ver or Odyssey, rather than using a computer.
References[edit]
- ↑ Greenberg, Andy. (2019). "A 'Permanent' iPhone Jailbreak Exploit Is Now Public." Wired.
- ↑ Goodin, Dan. (2014). "New untethered jailbreak for iOS 7.1.1 is released by Chinese team." Ars Technica.
- ↑ Whittaker, Zack. (2013). "How the 'Evasi0n' jailbreak works." ZDNet.
- ↑ Zelenko, Michael. (2019). "A new exploit could lead to a permanent jailbreak for 10 generations of iPhone." The Verge.
