(@hashcat) January 26, 2017
This is only useful if the backup was encrypted by setting a backup password on the iOS device. If the backup is not encrypted then all the files are in clear and there is nothing to bruteforce.
The keys used to encrypt the backup are stored in the BackupKeyBag, which can be found in the
Manifest.plist file. This keybag is a binary blob, the format of which has already been documented by researchers from Sogeti ESEC Lab.
I have written a simplified script which dumps the
Speeding up iOS Backups
iOS device backups usually take a while, depending on how much storage has been used on your device.
The iOS backup process is driven by the device itself, through the
BackupAgent process. This process treats the host PC like a dumb disk store, by sending it commands like
DLMessageGetFreeDiskSpace, etc. so that it can determine what has been backed up previously and what to send/update for incremental backups.
For password cracking, we don’t need the entire 64 GB (or God forbid, 128 GB) of data on the iOS device. We just need the
Manifest.plist, which is typically less than 50 KB. But because the backup process is controlled by the device and not the PC, we can’t simply ask it to send over that single file. Sometimes when we setup a VM with libimobiledevice, we might also not have allocated such a large virtual disk. Of course when I say “we”, I really mean “I”.