Re: you iso's may have been hacked

["Thomas Schmitt" <scdbackup@gmx.net>]

Hi,

Andrew F Comly wrote:
> Am I supposed to edit the script and put something in for magic=' '?

No. Magic is what an ISO 9660 should bear at byte offset 32768:
A byte with ASCII value 1 and five bytes saying "CD001":

  $ dd if=debian-8.4.0-amd64-netinst.iso bs=1 skip=32768 count=6 | od -c
  ...
  0000000 001   C   D   0   0   1

Your file yielded two blanks on this shell command

  dd if="/dev/sdb" bs=2048 skip=16 count=1 |
  dd bs=1 count=6 | od -x | head -1 | \
  awk '{print $2 " " $3 " " $4}'

Wheras an ISO is supposed to yield (on little-endian machine):

  4301 3044 3130

I get two blanks as result when i apply the command to a file which does
not have 32768 bytes or to which i have no read permission.
Given the fact that you run cmp under sudo, i'd guess it is about read
permission.

To my experience, /dev/sr0 is readable for the desktop user. So one would
not experience this difficulty with optical media.


Have a nice day :)

Thomas