AFC

AFC
AFC (Apple File Conduit) is a service that runs on every iPhone / iPod, which iTunes uses to exchange files with the device. It is jailed to the directory /private/var/mobile/Media, which is on the second (non-OS) partition. The AFC service is handled by /usr/libexec/afcd, and runs over the usbmux protocol.

AFC2
AFC2 is an additional AFC service, configured to allow access to the whole filesystem. Installing it and patching the fstab file for full write access is considered a bare-bones jailbreak. Up to iOS 7, the AFC2 service is added by editing the /System/Library/Lockdown/Services.plist file and adding a service that runs under root with access to the /|root filesystem. In case of iOS 8, services list with root access permission is moved to inside lockdownd itself. However, there is a function that extract plist data from binary itself in lockdownd. (related to CFPropertyListCreateWithData) We could use Mobile Substrate to hook the function by adding AFC2 service to its output.