Paradigm Shift researchers have published the technical details of usbliter8 , a new unpatchable vulnerability in the iPhone BootROM that allows arbitrary code execution on devices with Apple’s A12 and A13 chips. In a detailed technical post, the Paradigm Shift team explains that usbliter8 exploits both a hardware bug in the USB controller and a specific configuration weakness in the device’s firmware, rendering it unpatchable.
See also: Trump says Apple will make chips with Intel in the US
They coordinated the release with Apple Product Security and thanked Apple's security team for their prompt response and cooperation. This bug affects the following Apple SoCs: A12, S4, S5 , and A13.
Although the authors specifically mention only the iPhone, these SoCs are also found in other devices. They note that technical support for the A12X/Z is possible but not yet implemented, which could include the 2018 and 2020 iPad Pro series. The usbliter8 exploit works by sending specially formatted data to a device over USB while it is in DFU mode, confusing the USB controller and forcing it to write data to the wrong part of memory.
This gives an attacker with physical access control over the device's boot process, allowing them to execute their own code before iOS loads, bypassing signature checks and booting modified system software. Importantly, the exploit does not affect the Secure Enclave , which means that data such as passwords and encrypted user data remain safe.
See also: iPhone Air 2027: Apple is preparing a dual-camera upgrade
However, the PS team warns that while usbliter8 does not compromise the Secure Enclave itself, it opens up wider attack vectors that could compromise it. Their goal is to highlight the true impact of these hardware vulnerabilities and contribute to a broader understanding of modern SecureROM security.
The PS team explains that there are different methods for exploiting the exploit on A12, S4, S5, and A13 chips, with the A13 exploit being more complex due to its use of SecureROM's Pointer Authentication (PAC), a security feature designed to prevent code execution redirection. The researchers found a way to bypass the PAC by carefully corrupting various parts of memory in stages, eventually taking over the USB interrupt controller to execute their own code.
As this is an unpatchable exploit, the researchers note that affected users should be aware that upgrading to newer hardware remains the most effective mitigation. Interestingly, this exploit does not affect A11 or older chips, which are vulnerable to a separate unpatchable BootROM exploit known as checkm8. After checkm8 was discovered, it became the basis for several jailbreak tools targeting older iPhones and iPads, suggesting that a similar outcome may occur to devices affected by usbliter8.
See also: Pressure is mounting on Apple to offer better options to unionized workers
In addition to the technical analysis, the researchers published a PoC project on GitHub, which quickly gained popularity. Their detailed analysis of the process is highly technical, but offers valuable insights into usbliter8 and how it works.
🔒 Protect your privacy with Proton VPN
Swiss VPN from the creators of Proton Mail — strict no-logs policy, strong encryption, and built-in NetShield that blocks ads, trackers, & malware.
- ✔ No-logs, based in Switzerland (except 14-Eyes)
- ✔ NetShield: blocks ads, trackers & malicious domains
- ✔ Covers all devices — free version available
The link is an affiliate link — SecNews may receive a commission at no additional cost to you. It does not affect the independence of our article writing.
