Elcomsoft Phone Breaker is a graphics processing unit (GPU)-accelerated commercial tool from Elcomsoft, developed for the Windows platform. The tool can decrypt an encrypted backup file when the backup password is not available. The tool provides an option to launch a password brute-force attack on the encrypted backup if the backup password is not available. Elcomsoft Phone Breaker tries to recover the plain-text password that protects the encrypted backup, using a dictionary and brute-force attacks. Passwords that are relatively short and simple can be recovered in a reasonable amount of time. However, if the backup is protected with a strong and complex password, breaking it can take forever.

The tool is available here (including free trial version): https://www.elcomsoft.com/eppb.html.

To brute-force the backup password, perform the following steps:

1. Launch the Elcomsoft Phone Breaker tool and the tool's main screen will appear, as shown in the following screenshot:

2. Navigate to Password Recovery Wizard | Choose source | iOS device backup. Navigate to the backup file you want to crack, and select the Manifest.plist file.
3. Configure the brute-force pattern in the Attacks section and click on the Start button to start the brute-force attack, as illustrated in the following screenshot:

If the brute-force attack is successful, the tool displays the password on the main screen.

If you have an iPhone running iOS 11 or later, and its passcode, you can reset the actual password and make a backup with a new known password. Here is how to do it:

1. On the iPhone, go to Settings | General | Reset.
2. Choose Reset All Settings and enter the device's passcode. It's important to note that no data will be deleted.
3. Once the settings are reset, you can create a new backup with a password of your choice.