System security overview
Building on the unique capabilities of Apple hardware, system security is responsible for controlling access to system resources in Apple devices without compromising usability. System security encompasses the boot-up process, software updates, and protection of computer system resources such as CPU, memory, disk, software programs, and stored data.
The most recent versions of Apple operating systems are the most secure. An important part of Apple security is secure boot, which protects the system from malware infection at boot time. Secure boot begins in hardware and builds a chain of trust through software, where each step ensures that the next is functioning properly before handing over control. This security model supports not only the default boot of Apple devices but also the various modes for recovery and timely updates on Apple devices. Subcomponents like the T2 Chip and the Secure Enclave also perform their own secure boot to help ensure they only boot known-good code from Apple. The update system can even prevent downgrade attacks, so that devices can’t be rolled back to an older version of the operating system (which an attacker knows how to compromise) as a method of stealing user data.
Apple devices also include boot and runtime protections so that they maintain their integrity during ongoing operation. Apple-designed silicon on iPhone, iPad, Apple Watch, Apple TV, HomePod, and a Mac with Apple silicon provide a common architecture for protecting operating system integrity. macOS also features an expanded and configurable set of protection capabilities in support of its differing computing model, as well as capabilities supported on all Mac hardware platforms.