Key Notes
- A reset and airplane mode do not remove the BootROM flaws identified in older iPhones.
- The attacks require physical access and do not automatically reveal a protected wallet seed.
- OneKey’s founder recommends moving away from affected phones for seed storage.
OneKey founder Yishi has warned against treating an old iPhone as a secure crypto cold wallet simply because it has been factory-reset and disconnected from the internet. His October 31 warning focuses on flaws in the earliest stages of the boot process, which airplane mode does not remove.
The concern is physical access to the device. Yishi also stresses that a BootROM exploit alone does not reveal a seed phrase on models such as the iPhone XS or iPhone 11: the passcode, Secure Enclave and wallet’s own protections still matter.
Which iPhones Are Affected?
The warning identifies two generations of low-level exploits:
- checkm8, disclosed in 2019: Apple A5–A11 chips, corresponding to iPhone 4S through iPhone X.
- usbliter8, published in June 2026: A12 and A13 devices, including iPhone XS, XS Max, XR, the iPhone 11 family and the second-generation iPhone SE released in 2020.
CERT/CC’s checkm8 advisory confirms the older model range and explains that exploitation requires physical access, a connection to a computer and Device Firmware Update mode. It describes the exploit as nonpersistent: restarting ends changes made during that exploited session, but does not remove the underlying vulnerability.
Paradigm Shift’s original usbliter8 research, preserved in an archive, describes a USB-controller hardware bug combined with a firmware configuration flaw. The researchers demonstrated compromise of the application processor’s boot chain on A12 and A13 chips. This is separate from checkm8, despite the similar security concern.
Why a Reset or iOS Update Cannot Remove the Flaw
BootROM is startup code laid down when the chip is manufactured. Apple’s hardware security documentation describes it as immutable code that anchors the secure boot process. A factory reset changes the phone’s stored data and settings; it does not replace that code.
CERT/CC says the checkm8 flaw cannot be patched through a firmware update. The usbliter8 researchers likewise point to newer hardware as the most effective mitigation for their affected devices. Keeping iOS updated still matters for other vulnerabilities.
BootROM Access Is Not Automatic Access to a Seed
Apple describes the Secure Enclave as a separate security component with its own boot process and protections for encryption keys. Compromising the application processor’s boot chain therefore should not be equated with defeating every layer protecting a wallet.
CERT/CC specifically notes that checkm8 alone does not provide access to Secure Enclave- or Touch ID-protected information without the necessary authentication. Actual exposure depends on the model, software and how the wallet protects its secrets.
What the Warning Means for Crypto Holders
Yishi recommends moving away from affected phones for seed storage, using longer passcodes and keeping software current. If a seed may have been exposed, his advice is to create a completely new seed in a trusted environment and transfer the assets. Another address derived from the same seed would not remove that exposure.
This is a custody-risk warning, rather than evidence that every affected iPhone wallet has been compromised. Our crypto custody safety explainer examines the responsibilities that move to the holder with self-custody. Our coverage of Vitalik Buterin’s digital minimalism looks at a different risk: repeatedly loading wallet-related software through websites.
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