Just as there are endless ways to hack the password of a Windows operating system, you can also break the security of a Mac. The two methods that we review below are based on reset or reset the user password of a Mac with OS Leopard installed, and finally see how we can prevent anyone from unauthorized access to files on our Mac using these methods.
Method 1: Accessing a Mac with the installation disk 
If we have a Leopard install disc, it is easy to change the password for the administrator account. Insert the CD into your Mac and hold down the "c" while loading the OS. At a time when the installer will load the operating system. Once done go to "Utilities" -> "Reset Password." The window that appears will be prompted to enter the OS you wish to reset the password, choose the disk of the machine to hack. Select the user you want to reset the password in the dropdown menu. Enter a new password and voila! Remove the installation disc, restart your computer and connect with the new password.
Method 2: Single-user mode
If you do not have the installation disc of Mac OS, you can follow this alternative method. Start the computer by holding down CMD + S when you hear the startup tone. The Mac will be charged on a "single-user, open the command line after loading all necesario.Ingresa the following commands, pressing ENTER after entering each line, and waiting for the cursor appears again before loading the following command :
/ Sbin / fsck-fy
/ Sbin / mount-uw /
launchctl load / System / Library / LaunchDaemons / com.apple.DirectoryServices.plist
dscl. -Passwd / Users / username nuevopassword
Replace "username"With the name of the user whose password you will restore, and"nuevopassword"With the new password you will use to access the system.
If you do not know the user name, run the command ls / Users for a list of all user folders on the Mac, which are by default the name of each system user.
How to protect your Mac from being hacked by these two methods
You can prevent anyone can reset your password by using a "firmware password". Take the installation CD in your Mac, upload (hold down the "c" while loading the system) and go to "Utilities" -> "Firmware Password Utility" and generates a "Firmware Password". This will prevent others from resetting your password by one of the two methods mentioned initially.
