Hacklog Volume 1 Anonymity: it security & Ethical Hacking Handbook

; on Tails you can
find Nautilus Wiper
[131]
-
DBAN
[132]
(to format an entire partition WITHOUT using the OS – you’ll
have to burn a Live copy)
Shred on Linux
If you need to shred an entire partition, you can always use shred, a good old
command  line  tool.  Get  the  list  of  your  active  partitions.  You  may  want  to  use
the fdisk tool as follows:
$ sudo fdisk -l
so you can be sure you selected the correct path to the partition you wish to

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erase (let’s assume /dev/sdb). Now it’s time to wipe the partition. If time is not
on your side, you may want to use the fast wipe. This procedure is faster because
a blank value is written over every sector:
$ sudo shred -vzn 0 /dev/sdb
In this case, the -vzn parameter will tell shred
-
v, show progress
-
z, overwrite the last shredding step (to hide it)
-
n, define the number of iterations
-
0, having defined 0 iterations, the value will be NULL, then 0
This  will  make  the  partition  illegible,  since  the  sectors  won’t  contain  any
value. If, instead, you want to be confident on the result, you can always use the
tool to perform more complex tasks. For example, by launching:
$ shred -vzn 3 /dev/sdb
You  will  instruct  the  program  with  the  same  things,  but  in  this  case  three
iterations will be in place, tripling the sector rewriting steps, thus performing a
safer partition wipe. Shred is also a good program to delete individual files, by
using the --remove parameter, as in the following example:
$ shred --remove [filename]
DBAN for standalone
DBAN
[133]
(Darik’s Boot and Nuke) is a free and opensource tool allowing
file shredding over the entire hard disk. DBAN doesn’t depend on any operating
system in order to run, since it’s a GNU/Linux-base distro itself. To use it, then,
you need an external media (CD, USB etc...) and a short BIOS reconfiguration
(exactly  like  when  you  run  a  Linux  Live  USB).  DBAN  should  be  used  before
physically destroying a drive, in order to increase the chances of making the disk
illegible. Such tool offers different possible removal algorithms:

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•Quick Erase
1 step - Security Level: Low
This method only writes a blank value (0) in every sector. It’s only advisable if
the partitions will be rewritten, i.e. if you have to reinstall an Operating System
in it.
•RCMP TSSIT OPS-II
8 steps - Security Level: Medium
The  Royal  Canadian  Mounted  Police  Technical  Security  Standard  for
Information  Technology,  Annex  OPS-II:  Media  Sanitation.  This  module
implements a data randomization process.
•DoD Short
3 steps - Security Level: Medium
The quick method used by the American Department of Defense. It is based on
the steps 1,2 and 7 of the 5220.22-M model.
•DoD 5220.22-M
7 steps - Security Level: Medium
The standard method used by the American Department of Defense.
•Gutmann Wipe
35 steps - Security Level: High
The method described by Peter Gutmann in his document: “Secure Deletion of
Data from Magnetic and Solid-State Memory”.
•PRNG Stream
4/8 steps - Security Level: Medium/High
This  method  fills  the  device  sectors  using  a  pseudo-random  numeric  generator.
This  is  probably  the  best  method  for  the  next  generation  disks,  since  the
generation patterns vary. Such method offers a 4-step medium and a 8-step high
security level.
Using DBAN
Working  with  DBAN  doesn’t  require  any  particular  skill.  Once  it’s  Live-
mounted, it will appear as in Figure 32.

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