Apple’s iCloud lock for Macs is not very secure
One feature in Apple’s iCloud service for OS X is its lock option, which allows you to remotely set a PIN for your Mac through iCloud’s Find My iPhone service, and require that it be entered to boot the system.
This lock is similar to a firmware password for securing Mac systems. Not only does it prevent booting to alternative boot modes such as Safe Mode or Single User Mode, but it prevents loading in special hardware modes like Target Disk and Internet Recovery so the hard disk cannot be wiped or otherwise accessed.
Unlike the firmware password, however, the iCloud PIN is required to…