1. Forensication
A data backup and verification chat. Backing up and ripping data, making test beds and using equipment. This fire talk will cover: Write-blockers (hardware), dd, sha256sum, exiftool.

2. Disclaimer (01 of 02)
Formal forensics is a wide field and circles around the notion of backing up information, with minimal to no changes of the source data. Deeper forensic scope also involves analyzing the platform / Operating System, in order to determine OS level access (Example - thumbs.db folder indexers) versus manually viewed files.

3. Disclaimer (02 of 02)
This talk is based on using your own test data to use analytic tools and to understand how they work, without worrying about client liability. Use some test data you are familiar with, as this makes finding 'the needle in the haystack' tremendously easier to find patterns. Testing with the tools will give you the comfort to provide services for others.

4. Backstory
Howdy. I got into data imaging over the years from system building and also doing support for friends, family and businesses. Originally plugging a hard drive into another machine, I would target C:\Users and grab profile data. Also including application data and whatever else. After awhile I got into Linux for file ripping. Some files are protected in windows, even as a 2nd drive.

5. Tool usage
There are plenty of tools and applications with forms you can use. However they can be quite expensive. Personally, I like having built-in command line tools available. Especially for the sake of booting up a live cd at any location and being able to work, based on what I'm being asked to do or recover.

6. Write Blocker Imaging
Using a hardware write-blocker is an assured way to not modify the contents of the source drive. They are around $300 USD, so you have some cheaper options to do software write blocking... but if you forget to turn it on, you can contaminate your data source. (Such as browsing a folder, having windows make new thumbs.db files)

8. So how do you come up with the device names?
Imaging Drives
Image the drive with dd:
For a 500 GB HDD, it took about 3 hours. (results below)
So how do you come up with the device names?

9. Verifying disk image
Now that your drive is imaged, let's start verifying with the source drive, hooked up to the write-blocker.
Now that your drive is imaged, let's start verifying with the source drive, hooked up to the write-blocker.
Ignore the '^[[C' output as that was presses on the keyboard while the command ran.
In the above, I hooked up the cloned drive, powered up the Write-blocker, confirmed the disc mounted, then calculated the cryptographic checksum
Boom! It's a match :)

10. Cryptographic Checksums
There are plenty of options for generating checksums. While sha-1 and md5 are commonly used, there are some theoretical attacks against their memory space. Signature based anti-virus seems to have some clashes in the MD5 space.
Tools to get a checksum for a file are:
md5sum
sha1sum
sha256sum

11. File contents are as follows:
Checksum examples
Here I made a text file, saved it then calculated what the file’s crypto hash is (in sha256).
Making a second file with a single character change, I calculated that hash.
File contents are as follows:

12. Other checksum examples
ISO downloads and similar downloads tend to use MD5, so here are some extra output examples.
ISO downloads and similar downloads tend to use MD5, so here are some extra output examples.

13. Other checksum examples
ISO downloads and similar downloads tend to use MD5, so here are some extra output examples.
ISO downloads and similar downloads tend to use MD5, so here are some extra output examples.

14. Starting out with the image path, let’s wget a local copy.
BONUS ROUND - exiftool
Here I am grabbing the logo image from my site, then checking the image metadata for extra details.
Starting out with the image path, let’s wget a local copy.

15. Exiftool (continued)
Now that we have a local copy of ftb-logo.png, let’s see what details we get from the file.

16. Exiftool conclusion
Checking the Modify Date we see it was modified on 2009/10/13 around 5:45 PM. This matches up to the logo creation date.
Checking the Comment we see the image was edited in GIMP. I can confirm that as a fact, as I left the comment export option
Looking at the File Modification Date/Time that is consistent to when I uploaded that file into Wordpress for my front page of the site.
There are TONS of supported file types for use with the EXIFTOOL and this is only one tool. Have fun and explore!

17. Thank you(s)
I am Ryan (Mitch-kow-ski) I have the is my web home.