Passwords can be reset or bypassed on every operating system. On Windows, Linux, and Mac OS X, you can gain access to a computer’s unencrypted files after resetting the password — the password doesn’t actually prevent access to your files.
On other devices where you can’t gain access to the files, you can still reset the device and gain access to it without knowing a password. These tricks all require physical access to the device.
There are many ways to reset a Windows password. Windows allows you to create a password reset disk that can reset your password in an approved way — create a disk first and you can use it if you ever need it.
Resetting a password without an official tool is fairly simple. For example, the Offline NT Password & Registry Editor works well for this. First, you’ll need to boot from a special disc or USB drive — either a live Linux system or a specialized Offline NT Password & Registry Editor boot disc. The tool can edit the Windows registry, allowing you to clear the password associated with the user account. You can then boot into Windows and log into the account without a password.
Even if you’re using Windows 8 with a Microsoft account, you can always reset the password of the built-in Administrator account to gain access.
To protect against this, you could password-protect your BIOS and restrict booting from external devices. Someone with physical access to the PC could reset the BIOS password to bypass this. Encrypting your Windows system drive with something like BitLocker would prevent the registry from being accessed and modified with this tool — encryption is the only good protection.
We’ll use Ubuntu as a concrete example here. Ubuntu offers a recovery mode in its default Grub boot menu — select Advanced options for Ubuntu and select Recovery mode. You’ll see the boot menu while booting your computer — if you don’t, you can hold the Shift key as you boot and the menu will appear. You can easily boot directly to a root shell prompt from here.
This option isn’t necessary, as you can just press the e button to edit Ubuntu’s boot options and boot directly to a root shell prompt from within the main Grub menu. You’ll then be able to use the root shell to reset and change passwords on the system. If the Grub boot menu is locked and password-protected, you can still boot to Linux live media and change your password from there.
Once again, encryption would prevent your system from being accessed and modified without your encryption passphrase. We used Ubuntu as an example, but almost every Linux distribution uses Grub and few people set a Grub password.
Mac OS X
Macs have a built-in password reset tool, and it’s very easy to access. This option is available in recovery mode. You’ll need to restart your Mac by clicking the Apple menu and selecting Restart. Press and hold the Command + R keys as the computer boots and it will boot into recovery mode.
Click the Utilities menu in recovery mode, select Terminal, type resetpassword into the terminal, and press Enter. You’ll see the Reset Password utility, which allows you to reset the password of a any user account on the Mac. You can also access this tool from a Mac OS X installation disc.
To prevent your Mac’s password from being reset, you could enable FileVault disk encryption on your Mac, set a firmware password inside recovery mode, or both.
Your Chromebook’s user account password is your Google account password. You could reset your Google account password on the web to regain access.
Let’s say you have a Chromebook you want to use, but you can’t sign in. Perhaps you’ve forgotten the Google password associated with the device. Perhaps an old Google account is considered the device’s owner account. In this scenario, you can boot the Chromebook to the sign-in screen and press Ctrl + Shift + Alt + R at the same time. You’ll be prompted to factory reset your Chromebook with Powerwash. After you reset it, you can log in with another Google account and that Google account will be considered the owner account. This will erase all data on the device, but most Chromebook data is synced online.
There’s no way to gain access to a user’s files without their password on a Chromebook — those files are encrypted by default.
If you forget your Android’s lock screen code, you can reset it. Try an incorrect password, PIN, or pattern a few times and you’ll eventually see a “Forgot password,” “Forgot PIN,” or “Forgot pattern” option. You can then regain access to your device by entering the username and password of the Google account associated with your device.
If you don’t have this information either, you may be able to bypass the lock screen in other ways. This should be easy on a device with USB debugging enabled, as you can connect it to a computer and manipulate it over USB with adb — that’s why USB debugging is disabled by default.
You can’t bypass the lock screen without your Google account password unless there’s a hole open in the device — for example, USB debugging. If you want to use the device, you can still perform a factory reset from recovery mode — this will set the device back to its factory state, wiping the data on it . You can then log in and set up the device with another Google account.
iPhones, iPads, and iPod Touches are also built without a way to reset the password. Unlike on Android, you can’t just reset the device’s password with your Apple ID information. If you forget your iOS device’s password, you’ll have to perform a factory reset. However, if you’re syncing the device to an Apple ID and you still remember your Apple ID password, all your device’s data can be restored afterward thanks to iCloud backups.
You can do this in several ways. If you’ve set up Find My iPhone, you can visit the iCloud website and erase your device from there. If you’ve backed up your device to iTunes on a computer, you can connect the device to your computer and restore your device from an iTunes backup.
If you don’t have access to Find My iPhone and you’ve never backed up the device to iTunes, you can still reset the device using recovery mode. Turn off the device, press and hold the Home button, and then connect the device’s USB cable to your computer. If it doesn’t turn on automatically, turn it on. iTunes will tell you it’s detected a device in recovery mode and allow you to restore it to factory default settings.
Passwords keep honest people honest, and they ensure people can’t gain access to your device without knowing the tricks or looking them up. But, if someone has physical access to your device and wants to bypass the password, there’s nothing you can do to stop them. Even encrypting your files will only protect your personal data — they can always wipe the encrypted data and start over fresh.