Zimperium Analysis of checkm8

This report describes the checkm8 bootrom exploit disclosed in September 2019 that permanently compromises the SecureROM on affected Apple devices (A5–A11), enabling arbitrary code execution at boot when physical access and DFU mode are available. The exploit is unpatchable for impacted devices, can enable jailbreak capabilities or sideloading but is not persistent across reboots without additional vulnerabilities, and the document outlines affected models, attacker requirements, potential abuse scenarios, and detection/mitigation guidance.