OneKey Founder: iPhone 11 and earlier models have a chip-level vulnerability; Airplane Mode cannot guarantee mnemonic phrase security.

on November 1, OneKey founder Yishi issued a post warning that factory resetting an old iPhone, enabling airplane mode, and using it as a cold wallet to store mnemonic phrases does not fully guarantee asset security. iPhone 11 models and earlier contain BootROM chip-level vulnerabilities that cannot be patched via iOS updates, meaning attackers could still carry out attacks via physical contact even if the device is completely offline.

Yishi noted that iPhones from the 4S to X models are affected by the checkm8 vulnerability, while the usbliter8 vulnerability disclosed this June further impacts the iPhone XS, XR, 11 series, and second-generation iPhone SE. After gaining access to the device, attackers can use DFU mode and specialized USB hardware to execute code before iOS launches, which airplane mode cannot prevent. Nevertheless, the BootROM flaws themselves do not mean mnemonic phrases will be directly exposed, as the device passcode, Secure Enclave, and wallet app encryption still offer additional protection.

Yishi advises users who store mnemonic phrases on older iPhones to consider upgrading their devices, generating a completely new set of mnemonic phrases in a secure environment, and transferring assets to a new wallet rather than merely creating new addresses under the original mnemonic phrase. Users should also utilize strong passcodes, apply system updates promptly, and avoid leaving their devices outside their personal control for extended periods.