About System Integrity Protection on your Mac
System Integrity Protection is a security technology that helps protect your Mac from malicious software.
System Integrity Protection is a security technology designed to help prevent potentially malicious software from modifying protected files and folders on your Mac. System Integrity Protection restricts the root user account and limits the actions that the root user can perform on protected parts of the Mac operating system.
Before System Integrity Protection (introduced in OS X El Capitan), the root user had no permission restrictions, so it could access any system folder or app on your Mac. Software obtained root-level access when you entered your administrator name and password to install the software. That allowed the software to modify or overwrite any system file or app.
System Integrity Protection includes protection for these parts of the system:
Apps that are pre-installed with the Mac operating system
Paths and apps that third-party apps and installers can continue to write to include:
System Integrity Protection is designed to allow modification of these protected parts only by processes that are signed by Apple and have special entitlements to write to system files, such as Apple software updates and Apple installers. Apps that you download from the App Store already work with System Integrity Protection. Other third-party software, if it conflicts with System Integrity Protection, might be set aside when you upgrade to OS X El Capitan or later.
System Integrity Protection also helps prevent software from selecting a startup disk. Find out how to change your startup disk.