The boot process of Android-based devices is secured with the help of a manufacturer certificate. Each subsequent step is checked before it is executed. This ensures that the Android operating system starts unchanged.

When the boot loader is unlocked, this chain of trust is interrupted so that a modified operating system can start. Such changes to the boot process are partly supported by the manufacturer, and boot loaders are also sometimes unlocked via vulnerabilities.

In such cases, the Android security concept is bypassed or overridden, giving rise to new threats that have to be secured in another way.