I recently received an old iMac secondhand. I have no way to reach the original owner. I am trying to upgrade the OS software, but the prompts demand the administrator's name (which is auto-filled) and password (which I do not have). I understand why these security features are in place, but is there any way in the world for me to access Admin. privileges without the password?
MacOS – How to upgrade Mac OS without the administrator password
administratormacospasswordSecurity
Related Solutions
Boot to OS recovery, internet recovery or on older systems, with a Mac OS X DVD, then there's an option to change passwords.
You can follow an how-to here.
Yes, but this is not particularly a problem with rEFIt, it's intrinsic to the way firmware password and admin access relate to each other -- if you have either one, you can take control of the other. For instance, if you have admin access, you can disable or change the firmware password with nvram command, You can also change the boot volume with System Preferences, effectively bypassing the firmware password protection.
Basically, the firmware password is there to protect the integrity of the computer until the OS starts and can start enforcing its idea of access controls, at which point admin passwords are the relevant control. Don't think of firmware password as a higher-level control, it's more of a supplement.
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Best Answer
You can boot from installation media and use that to reset your password. To do this:
See this link for more information, including instructions on how to perform the reset without an installation disk.
Once the password is reset, you can perform an OS upgrade. Of course, as this is a second-hand machine, you may be better off doing a reinstall (in which case, just reinstall and don't bother resetting the administrator password first).