Forensics Boot
- Since BackTrack 4 and now BackTrack 5 you may have noticed that BackTrack has an option BackTrack Forensics but what exactly is that ?
For a long time now, Linux Live CDs have been very useful for
forensic acquisition purposes in instances where for one reason or
another you can’t utilize a hardware write blocker. When configured not
to automount drives, and a little bit of know how, a Linux Live CD can
be a wonderful software write blocker. For a Linux live CD to be
considered for this purpose however, it is of the utmost importance that
the use of the live CD in no way alters any data in any manner. That's
the main reason that BackTrack was rolled out in the past, BackTrack
would automount available drives and utilize swap partitions where
available, by doing this BackTrack could have caused all sorts of havoc,
changing last mount times, altering data on disk, and so on. But since
BackTrack 4 and now BackTrack 5 that's not the case anymore.
So, lets have the scoop. Forensic people are often detail oriented
and very conservative, so how do we know it is safe to use? Well, first
off the BackTrack 5 Live CD is based off of Casper, and contains no
filesystem automount scripts at all. The system initialization scripts
have been altered in the forensic boot mode so that BackTrack 5 will not
look for or make use of any swap partitions which are contained on the
system. All those scripts have been removed from the system.
To test this functionality, we have tested this boot mode with
multiple hardware configurations. For each test, we took a before MD5
snapshot of the system disks, booted BackTrack5 in forensic boot mode,
verified no file systems were mounted and swap was not in use, did a
number of activities on the system, then shut the system back down and
took an after MD5 snapshot. In comparing the two MD5 snapshots, in every
case they were a match, demonstrating no changes on the disks has been
made.
When you utilize Backtrack for forensics purposes, be sure you don’t
let it go through an unattended boot. Default boot for Backtrack is
standard boot mode, which will use swap partitions if they are present.
There is a nice long delay however, so you will have plenty of time to
select the proper boot mode. Also, please remember, this is a Linux
distribution. It is highly suggested that you become familiar with Linux
before use this, or any other Linux Live CD for any forensic purpose.
Also, be sure to check out the additional forensic tools added to
Backtrack 5. We have concentrated on the addition of imaging and triage
tools, but if you find that one of your favorite utilities is not in
place please let us know so we can look into having it added.
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