Daily Blog #508: Forensic Lunch Test Kitchen 10/15/18 - Examining the ObjectID index

Examining the ObjectID index by David Cowen - Hacking Exposed Computer Forensics Blog

Hello Reader,
          Tonight Matt Seyer virtually joined me for another test kitchen! We decided to examine the ObjectID index to determine what is really happening when a file is deleted and its ObjectID index entry is deleted. Matt presented his theory, Dr. Sylve contributed what he knew and the rest was solved with testing, tsk utilities, and python scripts.

Here is what we learned:

  • The ObjectID Index is a B-Tree with pages of entries of ObjectIDs
  • The last ObjectID in a page is the one most likely to survive in the slack space if it is deleted
  • ObjectIDs anywhere else in the page have a high chance of being overwritten when the b-tree is balanced unless they got saved from a previous page swap
  • istat won't give you the full path to a file, but you can get there if you are persistent 
  • The $logfile contains every changed page until its overwritten
We also have some new theories to test tomorrow night regarding USN and $Logfile interaction with the ObjectID Index! We should be testing those tomorrow night.

You can watch the video here:

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