During the last few months our lab received some damaged iTunes backups, and the extracted data contained errors. This fact forced us to find a way how to extract data from such backups effectively.
What can be the reason of a backup being damaged? We think, there are four main reasons:
- Electronic failures of iDevices
- Software-based errors
- iTunes conflicts with other software installed on the computer
- Forensic software bugs
Here is Magnet ACQUIRE error log:
2016-05-27 00:50:46 Info: Magnet ACQUIRE v2.0.0.0699
2016-05-27 00:50:46 Info: Operating System Version: 6.2.9200.0
2016-05-27 00:50:46 Info: Operating System Platform: Win32NT
2016-05-27 00:50:46 Info: Service Pack:
2016-05-27 00:50:46 Info: 64-Bit Operating System: True
2016-05-27 00:50:46 Info: 64-Bit Process: False
2016-05-27 00:50:46 Info: CLR Version: 4.0.30319.42000
2016-05-27 00:50:46 Info: Working Set: 44683264
2016-05-27 00:51:40 Info: Starting backup on device ‘1b85cec2c4d48781714a60cc873c4f5dab09baf8’.
2016-05-27 01:02:14 Info: Starting backup filesystem compressing from device ‘1b85cec2c4d48781714a60cc873c4f5dab09baf8’.
2016-05-27 01:26:02 Info: Initating file relay for device ‘1b85cec2c4d48781714a60cc873c4f5dab09baf8’.
2016-05-27 01:26:03 Error: An exception was caught while trying to read file relay for device ‘1b85cec2c4d48781714a60cc873c4f5dab09baf8’.
System.NotSupportedException: File relay is not supported on iOS 8+
at Magnet.Imager.Imaging.Plugins.Ios.FileRelay.AppleFileRelay.cd8260afba5f30039d3b89508b36a701e(String , IDeviceProperties , IntPtr , IEnumerable`1 , ILogger ) in File1020:line 96
at Magnet.Imager.Imaging.Plugins.Ios.FileRelay.AppleFileRelay.PerformFileRelayForSources(IDeviceProperties deviceProperties, String outputDirectory, String outputFilePath, IEnumerable`1 sources, ILogger logger) in File1020:line 54
at Magnet.Imager.Imaging.Plugins.Ios.Backups.ItunesBackupImager.Start(IDevice device, ILogger logger, String outputFolderPath, IImagingProgressReporter imagingProgressReporter, ICancellationToken cancellationToken, IDeviceImagingSettings deviceImagingSettings) in File1013:line 171
2016-05-27 01:26:03 Info: (Re)starting AFC service.
2016-05-27 01:26:03 Debug: Starting AFC service on the device using the lockdown escrow.
2016-05-27 01:27:13 Error: Unable to get filesystem extraction for device ‘1b85cec2c4d48781714a60cc873c4f5dab09baf8’.
System.InvalidOperationException: The call failed with return code AFC_E_MUX_ERROR.
at Magnet.IMobileDeviceWrapper.Afc.AfcDriver.c308c49f6daaf28ef75e86637cff93e1c(AfcError , String ) in File1200:line 222
at Magnet.IMobileDeviceWrapper.Afc.AfcDriver.GetFileSystemEntries(IntPtr afcClientHandle, String directoryPath) in File1200:line 84
at Magnet.IMobileDeviceWrapper.Afc.AppleFileConduit.c9d6086f5fe81acdc74e3701276fcf7ec.MoveNext() in File1201:line 80
at Magnet.IMobileDeviceWrapper.Afc.AppleFileConduit.c9d6086f5fe81acdc74e3701276fcf7ec.MoveNext() in File1201:line 91
at Magnet.IMobileDeviceWrapper.Afc.AppleFileConduit.c9d6086f5fe81acdc74e3701276fcf7ec.MoveNext() in File1201:line 91
at Magnet.IMobileDeviceWrapper.Afc.AppleFileConduit.c9d6086f5fe81acdc74e3701276fcf7ec.MoveNext() in File1201:line 91
at Magnet.IMobileDeviceWrapper.Afc.AppleFileConduit.c9d6086f5fe81acdc74e3701276fcf7ec.MoveNext() in File1201:line 91
at Magnet.IMobileDeviceWrapper.Afc.AppleFileConduit.c9d6086f5fe81acdc74e3701276fcf7ec.MoveNext() in File1201:line 91
at System.Linq.Enumerable.WhereEnumerableIterator`1.MoveNext()
at System.Linq.Buffer`1..ctor(IEnumerable`1 source)
at System.Linq.Enumerable.ToArray[TSource](IEnumerable`1 source)
at Magnet.Imager.Imaging.Plugins.Ios.Logical.FileSystemAcquirer.AcquireFilesystem(IntPtr deviceHandle, Boolean fromRootOfDevice, String outputFilePath, IImagingProgressReporter imagingProgressReporter, ILogger logger, ICancellationToken cancellationToken) in File1021:line 76
at Magnet.Imager.Imaging.Plugins.Ios.Backups.ItunesBackupImager.Start(IDevice device, ILogger logger, String outputFolderPath, IImagingProgressReporter imagingProgressReporter, ICancellationToken cancellationToken, IDeviceImagingSettings deviceImagingSettings) in File1013:line 194
And here are two examples of damaged iTunes backups:
Figure 1. A part of the damaged backup #1
Figure 2. A part of the damaged backup #2
The first backup extracted from a damaged iOS-device. The truth is that you can see all the data extracted on the figure. As you can see, there are no such important files, as Manifest.mbdb and Manifest.plist (you can read more about iTunes backup structure in this article).
The second backing up process finished with an error for an unknown reason. Despite the fact it looks like a normal iTunes backup, mobile forensic software can extract only some data from it, or can’t extract anything at all.
But both backups consist of files of non-zero size, so both contain data (pictures, video, call logs, SMS, MMS, contacts, etc.).
However caused, data extraction from a damaged iTunes backup with mobile forensic software finishes as one might expect:
Figure 3. The results of data extraction from a damaged iTunes backup with Oxygen Forensic
Could an examiner use mobile forensic software for data extraction from such backups? Yes. For example, Cellebrite UFED Physical Analyzer is able to extract some data from damaged iTunes backups. But, in our opinion, it doesn’t extract much data.
Figure 4. Data extracted from the second backup with UFED Physical Analyzer
What software could be used for data extraction from damaged iTunes backups?
We performed a research and to the conclusion that Belkasoft Evidence Center extracts more data from damaged backups than any other forensic software.
Figure 5. Data extracted from the second backup with Belkasoft Evidence Center
As you can see, Belkasoft Evidence Center extracted more data than UFED Physical Analyzer.
Discussion
In this article we have shown that data can be extracted from damaged iTunes backups. It’s very important for mobile forensic examiners, because in some cases such backups are the only sources of data, stored on iDevices.
In our research the best results we produced by Belkasoft Evidence Center. We don’t have a Magnet AXIOM license, so we can’t test this piece of software. Probably, we’d get same results as with Evidence Center. Also, UFED Physical Analyzer can be used to extract some data from damaged iTunes backups.
About the authors:
Interests: Computer, Cell Phone & Chip-Off Forensics
Interests: iOS forensics, Android forensics, Mac OS X forensics, Windows forensics, Linux forensics
